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Breaking voltage–bandwidth limits in integrated lithium niobate modulators using micro-structured electrodes

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Abstract

Electro-optic modulators with low voltages and large bandwidths are crucial for both analog and digital communication. Recently, thin-film lithium niobate modulators have emerged as a strong candidate for next generation electro-optic solutions. These modulators offer significantly improved voltage–bandwidth performances over the existing bulk lithium niobate modulators while preserving key material advantages such as linear response, high extinction ratio, high optical power handling ability, and low optical losses. However, reduced electrode gaps in miniaturized thin-film modulators lead to higher microwave losses, which limit electro-optic performances at high frequencies. Here we overcome this limitation to achieve a record combination of low RF half-wave voltage (${V_\pi}$) of 1.3 V while maintaining electro-optic response with 1.8 dB roll-off at 50 GHz using micro-structured electrodes. Our demonstration represents a significant improvement in voltage–bandwidth performance, one that is comparable to the performance gain in switching from legacy bulk to thin-film lithium niobate modulators. Such a micro-structured electrode design could enable sub-volt modulators with ${\gt}\! 100\;{\rm GHz}$ bandwidth.

© 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Corrections

Prashanta Kharel, Christian Reimer, Kevin Luke, Lingyan He, and Mian Zhang, "Breaking voltage-bandwidth limits in integrated lithium niobate modulators using micro-structured electrodes: erratum," Optica 8, 1218-1218 (2021)
https://opg.optica.org/optica/abstract.cfm?uri=optica-8-9-1218

1. INTRODUCTION

Low-voltage, broadband, and high-signal-quality electro-optic (EO) modulators are paramount to applications spanning from radio frequency (RF) analog links to digital optical communication networks. Today, most EO modulators require high drive voltages at frequencies ${\gt}{{50}}\;{\rm{GHz}}$ because of reduced microwave performance at such frequencies. Consequently, high-speed and high-gain electronic amplifiers are needed to drive these modulators, posing significant challenges for power consumption, linearity, signal-to-noise ratio, and cost. As the demand for a higher baud rate for digital communication and higher carrier frequency for analog links continue to grow, aforementioned challenges only exacerbate, as both the modulators’ efficiency and the electronic amplifier’s gain further diminish at higher microwave frequencies (e.g., ${\gt}{{100}}\;{\rm{GHz}}$).

The challenge of achieving low voltage at high microwave frequencies is universal across different photonics platforms, considering the stringent requirement of simultaneously retaining other desired modulator performances including good linearity, low insertion loss, high extinction ratio, and high-power handling ability. For traditional lithium niobate (LN) modulators based on ion-indiffusion and proton exchanged waveguides, a half-wave voltage (${V_\pi}$), which is the minimum voltage needed to switch from maximum to minimum transmission for amplitude modulators, of 3.5 V is typically needed at low microwave frequencies (e.g., 1 GHz). The EO response is attenuated by 3–6 dB for ${\gt}{{50}}\;{\rm{GHz}}$ [1]. This translates into a RF voltage requirement as high as ${\gt}{{7}}\;{\rm{V}}$ for modulation frequencies ${\gt}{{50}}\;{\rm{GHz}}$. On integrated platforms such as silicon, modulators typically have ${V_\pi}$ from 4–6 V and 35 GHz bandwidth [2,3]. Extending this performance to 50 GHz and beyond also points to a very high voltage (${\gt}{{10}}\;{\rm{V}}$) requirement. Indium phosphide (InP) modulators have achieved better voltage and bandwidth performances. For example, ${V_\pi} = 1.5\;{\rm{V}}$ and 80 GHz 3 dB bandwidth have been achieved on a differential RF drive architecture [4]. In addition, sub-volt single-drive modulators have also been achieved with 67 GHz 6 dB bandwidth on III–V platforms [5], but the extinction ratio was limited to 3 dB, and the drive voltage had to be increased to accommodate higher optical power [6]. Organic polymer modulators have shown excellent voltage–bandwidth performances [7] but a compromise in performance is often needed to improve stability for practical uses [8]. Plasmonic–organic hybrid modulators can provide extremely high bandwidths, although modulation voltage and on-chip insertion loss are relatively high [9].

Thin-film LN modulators emerged recently as a strong contender for next generation low-voltage and high-bandwidth EO solutions. This is because thin-film LN modulators offer significantly improved voltage–bandwidth performance over legacy LN platforms all while preserving key LN material advantages such as linear response, absence of modulation induced absorption, high optical power handling ability, and low optical loss. However, for thin-film LN modulators, ${V_\pi}$, especially at frequencies ${\gt}{{50}}\;{\rm{GHz}}$, remains ${\gt}{{3}}\;{\rm{V}}$, and the extrapolation to 100 GHz shows an expected ${V_\pi} \gt 4\;{\rm{V}}$ [1012]. Such performances have also been corroborated theoretically as being close to the traditional design limit [1316]. This level of RF voltages is still very high for typical electronics drivers. For example, a CMOS driver with a 100 GHz analog bandwidth typically produces ${\sim}0.5\;{\rm{V}}$ output voltage at high frequencies [17]. Therefore, a lower-voltage modulator would dramatically improve device performance such as energy consumption, sensitivity, and noise figures, which all scale quadratically with RF ${V_\pi}$ [18].

Here we break the voltage–bandwidth trade-off limit in integrated LN modulators using micro-structured electrodes that dramatically reduce microwave losses while preserving high EO modulation efficiency. We experimentally demonstrate a single-drive EO modulator with ${V_{\pi ,1\;{\rm{GHz}}}} = 1.3 \;{\rm{V}}$ and ${V_{\pi ,50\;{\rm{GHz}}}} = 1.6$ (EO roll-off of 1.8 dB). We further show that this design can be adapted to achieve sub-volt modulators with ${\gt}{{100}}\;{\rm{GHz}}$ 3 dB EO bandwidth. At the same time, we maintain an on-chip loss of ${\lt}{{1}}\;{\rm{dB}}$ and high extinction ratio of 20 dB. Notably, the performance gain achieved using the micro-structured electrode design over regular electrodes on thin-film LN is comparable to the improvement attained when transitioning from bulk to thin-film LN modulators.

2. SEGMENTED TRAVELING WAVE LN MODULATOR DESIGN

The EO modulator employs a traveling wave design on a x-cut thin-film LN-on-insulator (LNOI) platform, where an input light is split into two arms of a Mach–Zehnder interferometer (MZI) and co-propagates with a microwave drive signal in a transmission line electrode [10]. The traveling microwave signal modulates the light throughout the lengths of the electrodes in a push–pull configuration, inducing a phase advance in one arm and phase delay in the other. In principle, traveling wave modulators in LN with a long enough electrode can achieve terahertz bandwidth and millivolt driving voltage since the Pockels effect takes place on femtosecond time scale [19]. In practice, bandwidth and voltage performances are limited by four key factors: (1) microwave loss in the transmission line causing the driving voltage to be attenuated over the length of the electrode; (2) finite velocity mismatch between the traveling electrical and optical signals causing modulation to cease accumulating; (3) design trade-offs that reduce modulation efficiency per unit length requiring even longer devices to achieve a low voltage, thus further limiting the bandwidth; and (4) impedance mismatch with external electrical circuitry causing reflections and increased voltage.

In other words, to achieve high-bandwidth and low-voltage operations on LN, the effective index of the electrical signal should match the group index of the optical signal [20]; microwave loss (i.e., the attenuation of electrical current flowing in the direction of the traveling wave) should be low; the electric field should be strong between the electrode gaps so that the modulation is phase matched and can efficiently accumulate along the traveling wave direction; and the impedance of the modulator should be matched with external drivers so that power can be efficiently delivered to the transmission line.

While modulation efficiency can be increased and velocity matching is more readily maintained in thin-film LN modulators when compared to legacy bulk LN modulators [21], microwave loss unfortunately increases significantly in integrated LN designs [13,21,22]. Microwave electrode losses originate mainly from two sources: substrate absorption loss and ohmic conductor loss from the finite resistivity of metals, with the latter being the dominant loss mechanism in existing thin-film LN modulators. This is because the smaller electrode gaps in thin-film LN modulators, enabled by high confinement optical waveguides, improve key efficiency metrics such as the half-wave voltage length product (${V_\pi} \cdot L$) at the expense of dramatically increased ohmic loss. The narrow metal gap, on the order of a few micrometers, causes the electrical current to crowd close to the gap from the largely increased capacitance, effectively reducing the conductor area and thus increasing RF loss. As a result, non-ideal trade-offs such as increasing the electrode gap, which lowers modulation efficiency (increases ${V_\pi} \cdot L$), and/or reducing electrode length have been predicted to maintain flat RF responses (Table 1) [13,14,16]. Such design trade-offs lead to underutilization of a tightly confined optical mode for efficient EO modulation on integrated LN platforms.

In contrast, our design maintains high modulation efficiency (low ${V_\pi} \cdot L$) on a thin-film LN platform while reducing electrode losses and maintaining a velocity matching condition. To achieve this, we employ a traveling wave electrode with micro-structures to control the flow of currents. The micro-structured electrodes consist of rectangular channel electrode regions, like conventional coplanar transmission line designs, and segments extending out from the main electrode [Figs. 1(a) and 1(b)]. The segments prevent electrical current from flowing into the closest gap region, while allowing the current to be distributed more uniformly in the wide channel region. As a result, the effective conductor size is increased, and the ohmic loss in the electrode is reduced without having to increase the gap ($g$) between the electrodes [Figs. 1(c) and 1(d)].

Tables Icon

Table 1. Comparison of Simulated Performance for Various Electrode Designs

 figure: Fig. 1.

Fig. 1. Low-voltage high-bandwidth traveling-wave integrated lithium niobate (LN) modulator with segmented electrodes. (a) Artistic top view of the modulator design (not to scale) where RF signal co-propagates with the optical signal. (b) Scanning electron microscope image of the fabricated device. Scale bar: 50 µm. (c) Artistic angled view of a regular electrode design. Current (red) crowds at edges of the conductors. (d) Artistic angled view of a segmented design. Current crowds less and distributes more uniformly. (e) Cross sectional view of the phase shifter. Design parameters $(g,h,s,t,r,c,{w_s}) = (5,6,2,6,45,5,100)\;{{\unicode{x00B5}{\rm m}}}$.

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Such micro-structured electrodes (also known as segmented electrodes) have been used previously on semiconductor substrates to help velocity matching [23] and also moderately improve conductor loss in III–V and silicon modulators [24,25]. On insulators with high permittivity such as LN (${\epsilon _{{\rm{LN}}}} \sim 30$), segmented structures have been previously explored [26,27] but improvement on RF performances have not been demonstrated. While the RF loss improvement with such an electrode design on an insulator was unknown, a collateral and deleterious effect is the significant reduction in microwave velocity of the segmented design relative to a rectangular electrode design, due to the increased capacitance per unit length from the segments. For a traditional LN substrate, this slow wave effect would be detrimental for velocity matching since RF velocity is already slower than optical group velocity to begin with [1]. On a thin-film LN-on-silicon substrate, the slow wave effect is also undesirable since a silicon substrate with a reasonably thick silicon dioxide (${\rm{Si}}{{\rm{O}}_2}$) insulating layer can already provide a good velocity match between light and microwave [10,21].

Here we instead take advantage of the slow wave effects by using a quartz substrate, which has nearly ideal microwave properties with low permittivity (${\epsilon _{{\rm{Qz}}}} = 4.5$) and microwave absorption tangent $ {\lt} 10^{- 4}$ [28]. In addition, quartz wafers are cost effective and have excellent thermal and mechanical properties. On a x-cut thin-film LN (600 nm thick) with a quartz substrate, one obtains a RF phase index in the 1.7–1.9 range for conventional co-planar electrodes with ground–signal–ground (GSG) configurations, which is significantly lower than the typical optical group index in the 2.2–2.3 range for high-confinement LN waveguides. While this velocity mismatch would be detrimental for high-speed operations for regular electrode designs [29,30], it provides an opportunity to use a segmented design that slows the microwave velocity as well as pushes the current away from the narrow gaps.

As a low permittivity substrate is chosen to provide a low RF index for a rectangular GSG electrode, the segments can be added as extensions on the rectangular channel electrodes. Such extensions essentially increase the capacitance per unit length of the GSG line without inducing significant inductance change, resulting in an increase in the RF index and thus slowing down the microwave signal. The geometry of the extension should be designed such that current is confined in the channel region while pushed far away from the gap. T-shaped rails are well modeled geometries on other material platforms to achieve such a goal [31]. We show that the segmented electrode design can be readily used on LN-on-quartz wafers to achieve a RF index in the 2.2–2.3 range, which can be fine-tuned by the dimensions of the segments to match the optical group velocity in LN precisely. Importantly, as opposed to marginal RF loss improvements in other semiconductor platforms, the segmented electrode design in insulating thin-film LN reduces the RF loss substantially.

We simulated the electrical performance of a few segmented electrode designs and regular electrodes using finite element methods (Ansys HFSS) and compare the results with bulk LN designs in Table 1. For regular electrodes on silicon, the film stacks used were LN: 600 nm, ${\rm{Si}}{{\rm{O}}_2}$: 2 µm, and Si: 500 µm. For electrodes on a quartz substrate, the film stacks were LN: 600 nm, ${\rm{Si}}{{\rm{O}}_2}$: 2 µm, and quartz: 500 µm. In all cases, the electrode material is gold and thickness is set at 800 nm. The performance parameters are extracted from full 3D simulations with a simulated electrode length of 200 µm, which are then scaled to the full required electrode length. The results are shown in Table 1, which indicates the modulators’ 3 dB bandwidth limit can be improved many times more for the segmented electrodes than regular electrodes for the same designed DC ${V_\pi}$. The ${V_\pi}L$ product is simulated by numerically integrating the optical mode (Ansys Lumerical) overlap with an applied electric field in the active LN region [21].

 figure: Fig. 2.

Fig. 2. Measured RF losses and phase indices of a 10 mm long regular electrode on LN-on-silicon and a segmented electrode on LN-on-quartz. (a) Measured RF losses on linear frequency axis. (b) Measured RF losses on square-root frequency axis. (c) Measured RF phase indices.

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3. MEASUREMENTS AND ANALYSIS

We fabricated LN modulator devices using a wafer (NanoLN) consisting of a 600 nm thick x-cut LN thin-film on a 500 µm thick quartz handle with a 2 µm ${\rm{Si}}{{\rm{O}}_2}$ layer in between. We patterned the optical device with electron beam lithography and etched 350 nm of LN film to define integrated waveguides that have width ${w_o} = 2\;{{\unicode{x00B5}{\rm m}}}$ [Fig. 1(e)] in the active electrode region using a previously reported method [32]. The device was then cladded with 1 µm thick ${\rm{Si}}{{\rm{O}}_2}$, deposited by chemical vapor deposition. We then patterned 800 nm thick gold electrodes with a self-aligning lift-off process, where the ${\rm{Si}}{{\rm{O}}_2}$ is etched and filled with the metal layer using the same resist layer [Fig. 1(e)].

We show that the segmented electrode completely transformed the RF performance while preserving other desired modulator performances. We measured the electrical loss on the segmented electrode using a 50-$\Omega$ vector network analyzer (VNA) with all the RF components up to the device de-embedded. The electrodes were connected by a pair of microwave probes at the two ends for launching and extraction of the microwave signal. We obtained RF loss of 2 dB/cm in the segmented electrode at 50 GHz in comparison to 7 dB/cm in the regular electrode design with identical gold electrode thickness of 800 nm and electrode gap $g = 5 \;{{\unicode{x00B5}{\rm m}}}$ [Fig. 2(a)]. We also measured a RF phase index of $2.23 \pm 0.01$ at 50 GHz [Fig. 2(c)], which agrees with our simulation (Table 1). This value provides good velocity matching to the optical group index of the waveguide transverse electric mode, which is simulated to be 2.25 (Lumerical).

The measured RF losses have excellent agreement with theory. Ohmic loss in the electrode ${\alpha _{{\rm{RF}}}}$ is $\propto L{f^{1/2}}$ as a result of the skin effect in metal [33], where $L$ is the length of the electrode, and $f$ is microwave frequency. We measured regular electrodes on thin-film LN having ${\alpha _{{\rm{RF,reg}}}} = 0.69\;{\rm{dB}}\;{\rm{c}}{{\rm{m}}^{- 1}}\;{\rm{GH}}{{\rm{z}}^{- 1/2}}$ compared to ${\alpha _{{\rm{RF,seg}}}} = 0.26\;{\rm{dB}}\;{\rm{c}}{{\rm{m}}^{- 1}}\;{\rm{GH}}{{\rm{z}}^{- 1/2}}$ for the segmented electrodes. The square root dependence of the loss is clear in Fig. 2(b), corroborating the assumption that ohmic loss is the dominate source of RF attenuation. Note that microwave absorption loss has a linear dependence with microwave frequency so it would show up as a superlinear contribution in Fig. 2(b) at high frequencies. Our results show that the linear loss is still too small in comparison to conductor loss up to 50 GHz. Based on our fitting, we estimate an upper limit for RF absorption on the LN-on-quartz substrate of $0.007\;{\rm{dB}}\;{\rm{c}}{{\rm{m}}^{- 1}}\;{\rm{GH}}{{\rm{z}}^{- 1}}$, which translates to less than 0.35 dB/cm at 50 GHz and 0.7 dB/cm at 100 GHz. Using a loss tangent of 0.004 for LN bulk crystals [34], our simulation produced absorption loss of $0.003\;{\rm{dB}}\;{\rm{c}}{{\rm{m}}^{- 1}}\;{\rm{GH}}{{\rm{z}}^{- 1}}$, which agrees well with the limit estimated by our measurements.

We characterized the EO performance of the modulators using a telecom wavelength tunable laser at 1560 nm. We coupled light through a pair of grating couplers with total insertion loss of 13 dB and on-chip loss of $1 \pm 0.5\;{\rm{dB}}$ estimated by comparing transmission loss of a pair of gratings couplers with and without the modulator. The loss measurement is also corroborated with passive waveguide propagation loss measured using a microring resonator on the same chip, which shows a propagation loss of 0.34 dB/cm [32]. The majority of the optical loss results from the 6 dB/facet loss of grating couplers due to the absence of a high-index substrate. The total insertion loss can be dramatically reduced by using edge couplers [35], or buried metal back reflectors [36] to ${\sim}4\;{\rm{dB}}$. We obtained DC ${V_\pi}$ of 1.35 V on an oscilloscope for a 20 mm long modulator. The extinction of the modulator was measured to be 20 dB [Fig. 3(a)], which can be further improved from better fabrication control and Y-splitter design [37,38].

 figure: Fig. 3.

Fig. 3. Electro-optic performance of segmented LN modulators. (a) Measured DC ${V_\pi}$ and extinction for a 20 mm long modulator. (b) Measured EO responses and electrical reflections (${S_{11}}$) referenced to RF ${V_\pi}$ at 1 GHz for a 10 mm and a 20 mm long modulator. The responses are normalized to photodiode electric signal, i.e., ${V_{\pi ,{{3}} {\text -} {\rm{dB}}}} \sim 1.4{V_{\pi ,1\;{\rm{GHz}}}}$ and ${V_{\pi ,{{6}} {\text -} {\rm{dB}}}} \sim 2{V_{\pi ,1\;{\rm{GHz}}}}$. The length independent ripples in the EO response curves are caused by uncertainty in photodetector response (Newport 1014), which is numerically de-embedded from manufacture’s data sheet.

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The ultralow RF loss enabled measured EO responses of only 1.8 dB attenuation for the 20 mm long modulator at 50 GHz compared to reference ${V_\pi}$ at 1 GHz [Fig. 3(b)]. We choose to reference the EO roll-off to the conventional ${V_{\pi ,1\;{\rm{GHz}}}}$, since RF ${V_\pi}$ is overall a better metric for gauging modulator performances. This is because LN modulators at frequencies close to DC are prone to additional slow effects such as a photorefractive effect that can lead to over- or underestimation of ${V_\pi}$. Throughout the paper, we adopt the convention that EO bandwidth is normalized to photodiode electric signal, i.e., ${V_{\pi ,3 {\text -} {\rm{dB}}}} \sim 1.4{V_{\pi ,1\;{\rm{GHz}}}}$ and ${V_{\pi ,6{\text -} {\rm{dB}}}} \sim 2{V_{\pi ,1\;{\rm{GHz}}}}$. Our measurements at 1 GHz using a Bessel function transform method [39] indicate ${V_{\pi ,1\;{\rm{GHz,20}} {\text -} {\rm{mm}}}} = 1.3 \pm 0.1 \;{\rm{V}}$. In other words, the RF ${V_\pi}$ at 50 GHz is a record low of only 1.6 V. We also measured a 10 mm modulator with a segmented electrode, which shows only 0.8 dB roll-off at 50 GHz relative to a measured ${V_{\pi ,1\;{\rm{GHz,10}} {\text -} {\rm{mm}}}} = 2.3 \pm 0.2 \;{\rm{V}}$. The electrical reflection (${S_{11}}$) from the electrode for both cases is maintained below $- 15\;{\rm dB}$. The measured RF ${V_\pi}$ for the 20 mm electrode is higher than expected due to finite resistance and RF insertion loss of the thin metal electrode, which can be improved with thicker metals.

 figure: Fig. 4.

Fig. 4. Comparison of micro-structured modulator performance to prior designs and predictions on high frequency performances. (a) Measured voltage–bandwidth (1 dB) performance comparison of legacy LN ($0.3\;{\rm{dB}}\;{\rm{c}}{{\rm{m}}^{- 1}}\;{\rm{GH}}{{\rm{z}}^{- 1/2}}$, $15\;{\rm{V}} \cdot {\rm{cm}}$), thin-film regular LN ($0.69\;{\rm{c}}{{\rm{m}}^{- 1}}\;{\rm{GH}}{{\rm{z}}^{- 1/2}}$, $2.1\;{\rm{V}} \cdot {\rm{cm}}$), and thin-film segmented LN modulators ($0.26\;{\rm{c}}{{\rm{m}}^{- 1}}\;{\rm{GH}}{{\rm{z}}^{- 1/2}}$, $2.3\;{\rm{V}} \cdot {\rm{cm}}$). The shaded areas correspond to improved design space with other substrates. (b) Predicted performances of 20 mm long electrode for regular and segmented design up to 200 GHz bandwidth. Material legends indicate the substrate handle. (c) Velocity matching tolerances of segmented modulator with two different lengths. Curves represent EO bandwidth.

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4. DISCUSSION

The flexibility of substrate engineering and micro-structured electrode design enabled dramatic performance improvements over standard electrode designs on silicon substrates. Here we compare the voltage and 1 dB EO bandwidth limits of legacy modulators [40,41], regular thin-film LN modulators [1012], and segmented thin-film LN modulators [Figs. 4(a)]. We choose 1 dB EO bandwidth as a benchmark to accommodate the very small roll-off measured on the segmented designs. The solid lines in Fig. 4(a) represent the performance for typical electrode losses and ${V_\pi} \cdot L$ values on each platform. Due to the current crowding effect, electrodes on thin-film LN typically have 5–7 dB/cm RF loss at 50 GHz (${\alpha _{{\rm{RF}}}} \sim 0.7 {-} 1\;{\rm{dB}}\;{\rm{c}}{{\rm{m}}^{- 1}}\;{\rm{GH}}{{\rm{z}}^{- 1/2}}$), which is much higher than typical RF loss in legacy modulators of 2 dB/cm at 50 GHz (${\alpha _{{\rm{RF}}}} \sim 0.3\;{\rm{dB}}\;{\rm{c}}{{\rm{m}}^{- 1}}\;{\rm{GH}}{{\rm{z}}^{- 1/2}}$). Still, thin-film LN modulators outperform legacy designs due to the nearly five times reduction in ${V_\pi} \cdot L$. On the segmented electrode platform, the ${V_\pi} \cdot L$ is maintained close to the regular electrode and at the same time with improved ${\alpha _{{\rm{RF}}}}$ to $0.26\;{\rm{dB}}\;{\rm{c}}{{\rm{m}}^{- 1}}\;{\rm{GH}}{{\rm{z}}^{- 1/2}}$. Shown as the shaded area in Fig. 4(a), the RF loss limit of the segmented electrode design could be increased further using an even lower-permittivity substrate such as fused silica (${\epsilon _{{\rm{fs}}}} = 3.8$) or air (${\epsilon _{{\rm{air}}}} = 1$). A decrease in substrate permittivity allows longer segments, which further reduce current crowding while still maintaining sufficient velocity matching conditions. In air cladded cases, microwave loss as low as $0.15\;{\rm{dB}}\;{\rm{c}}{{\rm{m}}^{- 1}}\;{\rm{GH}}{{\rm{z}}^{- 1/2}}$ is within reach for such designs according to simulation. It is evident that the new segmented design leads to a performance gain similar to what regular thin-film design has achieved over legacy bulk LN.

Next, we provide insight into the ultrahigh bandwidth performances for the segmented design. We extrapolate the expected voltage–bandwidth performance based on the measured RF loss values to 200 GHz [Fig. 4(b)]. We see that for the same electrode length of 20 mm, the significant reduction of RF loss in the segmented design could lead to a 180 GHz conductor loss limited 3 dB bandwidth in comparison to a regular thin-film modulator that has 40 GHz loss limited bandwidth [Fig. 4(b)]. This simple analysis above provides the achievable bandwidth for a low-voltage device under ideal velocity and impedance matching conditions and minimal additional RF loss channels. Practically, the bandwidth may be limited by finite velocity mismatch and other possible channels of RF losses.

To quantify the velocity matching requirement, we plot the expected EO roll-offs for various velocity matching conditions for a 10 mm and a 20 mm long electrode [Fig. 4(c)], which shows that ${\gt}{{100}}\;{\rm{GHz}}$ 3 dB bandwidth can be obtained for a velocity matching tolerance of ${\pm}1.5\%$ and ${V_{\pi ,1\;{\rm{GHz}}}} \sim 1\;{\rm{V}}$. Such a level of the velocity matching requirement, which is identical for segmented and regular thin-film modulator designs [21], is routinely achieved on bulk LN platforms [20,22]. The fabrication requirement to meet such a level of velocity matching on the thin-film platform can also be readily achieved. For example, a film thickness variation of ${\pm}10\;{\rm{nm}}$ will change the RF index by 0.005 and optical index by 0.001. As processes further mature and approach that of silicon-on-insulator technologies, where better than 2 nm film and etch uniformity can be achieved over 300 mm wafers [42], it is reasonable to expect that velocity control can be achieved well beyond the required 1% accuracy.

Still, at ultrahigh microwave frequencies, the segments are expected to cause frequency dependent phase shift [24] due to the Bragg resonance associated with the periodic segments. For the design we employed with 50 µm short segments, less than 1% velocity ripple is expected up to 200 GHz [23,43]. Two methods can be employed to further alleviate such limitations for ultrahigh frequencies. First, a shorter electrode would have increased bandwidth for the same level of velocity tolerance. Second, a segmented structure with a smaller period can increase the Bragg resonance, thus further reducing dispersion.

Finally, another RF loss contribution is substrate radiation loss, which dominates traditional LN modulators at frequencies ${\gt}{{70}}\;{\rm{GHz}}$, due to the relatively large electrode gaps. In thin-film LN platforms, the much narrower electrode gaps in both regular and segmented transmission lines lead to well-confined microwave modes that have dramatically reduced substrate loss, as predicted by theory [44] and demonstrated experimentally from frequencies of 100 GHz up to 500 GHz [30]. Future experiments are needed to validate the exact radiation loss contribution at ultrahigh frequencies.

5. CONCLUSION

We have demonstrated an integrated LN EO modulator with an ultra-flat frequency response and low RF ${V_\pi}$ using a segmented traveling-wave electrode on a low-permittivity substrate, with measured ${V_{\pi ,1\;{\rm{GHz}}}} = 1.3 \;{\rm{V}}$ with 1.8 dB roll-off at 50 GHz (${V_{\pi ,50\;{\rm{GHz}}}} = 1.6 \;{\rm{V}}$). Based on these measurements and numerical simulations, we estimate that a segmented electrode on thin-film LN-on-quartz opens up the possibility of achieving sub-volt modulators while having a 3 dB bandwidth ${\gt}{{100}}\;{\rm{GHz}}$. We believe that the significantly improved EO modulation performance in micro-structured thin-film LN modulators will lead to a paradigm shift for both analog and digital ultrahigh-speed RF links. For example, for digital applications with sub-volt modulators, high-speed electronic drivers may have a largely reduced gain–bandwidth requirement or possibly be completely by-passed with the modulators driven directly from electronic processors [45].

Disclosures

Prashanta Kharel, Christian Reimer, Kevin Luke, Lingyan He, and Mian Zhang: HyperLight Corporation (I,E,P).

REFERENCES

1. E. Wooten, K. Kissa, A. Yi-Yan, E. Murphy, D. Lafaw, P. Hallemeier, D. Maack, D. Attanasio, D. Fritz, G. McBrien, and D. Bossi, “A review of lithium niobate modulators for fiber-optic communications systems,” IEEE J. Sel. Top. Quantum Electron. 6, 69–82 (2000). [CrossRef]  

2. J. Zhou, J. Wang, L. Zhu, Q. Zhang, Q. Zhang, and J. Hong, “Silicon photonics carrier depletion modulators capable of 85Gbaud 16QAM and 64Gbaud 64QAM,” in Optical Fiber Communication Conference (Optical Society of America, 2019), paper Tu2H.2.

3. M. Li, L. Wang, X. Li, X. Xiao, and S. Yu, “Silicon intensity Mach-Zehnder modulator for single lane 100 Gb/s applications,” Photon. Res. 6, 109–116 (2018). [CrossRef]  

4. Y. Ogiso, J. Ozaki, Y. Ueda, H. Wakita, M. Nagatani, H. Yamazaki, M. Nakamura, T. Kobayashi, S. Kanazawa, Y. Hashizume, H. Tanobe, N. Nunoya, M. Ida, Y. Miyamoto, and M. Ishikawa, “80-GHz bandwidth and 1.5-v VPI InP-based IQ modulator,” J. Lightwave Technol. 38, 249–255 (2020). [CrossRef]  

5. S. Dogru and N. Dagli, “0.77-V drive voltage electro-optic modulator with bandwidth exceeding 67 GHz,” Opt. Lett. 39, 6074–6077 (2014). [CrossRef]  

6. P. Bhasker, J. Norman, J. Bowers, and N. Dagli, “Low voltage, high optical power handling capable, bulk compound semiconductor electro-optic modulators at 1550 nm,” J. Lightwave Technol. 38, 2308–2314 (2020). [CrossRef]  

7. C. Kieninger, Y. Kutuvantavida, D. L. Elder, S. Wolf, H. Zwickel, M. Blaicher, J. N. Kemal, M. Lauermann, S. Randel, W. Freude, L. R. Dalton, and C. Koos, “Ultra-high electro-optic activity demonstrated in a silicon-organic hybrid modulator,” Optica 5, 739–748 (2018). [CrossRef]  

8. C. Kieninger, Y. Kutuvantavida, H. Miura, J. N. Kemal, H. Zwickel, F. Qiu, M. Lauermann, W. Freude, S. Randel, S. Yokoyama, and C. Koos, “Demonstration of long-term thermally stable silicon-organic hybrid modulators at 85c,” Opt. Express 26, 27955–27964 (2018). [CrossRef]  

9. M. Burla, C. Hoessbacher, W. Heni, C. Haffner, Y. Fedoryshyn, D. Werner, T. Watanabe, H. Massler, D. L. Elder, L. R. Dalton, and J. Leuthold, “500 GHz plasmonic Mach-Zehnder modulator enabling sub-THz microwave photonics,” APL Photon. 4, 056106 (2019). [CrossRef]  

10. C. Wang, M. Zhang, X. Chen, M. Bertrand, A. Shams-Ansari, S. Chandrasekhar, P. Winzer, and M. Loncar, “Integrated lithium niobate electro-optic modulators operating at CMOS-compatible voltages,” Nature 562, 101–104 (2018). [CrossRef]  

11. M. Xu, M. He, H. Zhang, J. Jian, Y. Pan, X. Liu, L. Chen, X. Meng, H. Chen, Z. Li, X. Xiao, S. Yu, S. Yu, and X. Cai, “High-performance coherent optical modulators based on thin-film lithium niobate platform,” Nat. Commun. 11, 3911 (2020). [CrossRef]  

12. A. N. R. Ahmed, S. Shi, A. Mercante, S. Nelan, P. Yao, and D. W. Prather, “High-efficiency lithium niobate modulator for K band operation,” APL Photon. 5, 091302 (2020). [CrossRef]  

13. A. Honardoost, F. A. Juneghani, R. Safian, and S. Fathpour, “Towards subterahertz bandwidth ultracompact lithium niobate electrooptic modulators,” Opt. Express 27, 6495–6501 (2019). [CrossRef]  

14. A. Honardoost, R. Safian, A. Rao, and S. Fathpour, “High-speed modeling of ultracompact electrooptic modulators,” J. Lightwave Technol. 36, 5893–5902 (2018). [CrossRef]  

15. R. Safian, M. Teng, L. Zhuang, and S. Chakravarty, “Foundry-compatible thin film lithium niobate modulator with RF electrodes buried inside the silicon oxide layer of the SOI wafer,” Opt. Express 28, 25843–25857 (2020). [CrossRef]  

16. W. Peter Orlando, V. Forrest, Z. Jie, L. Huiyan, and M. Shayan, “Design of high-bandwidth, low-voltage and low-loss hybrid lithium niobate electro-optic modulators,” J. Phys. Photon. 3, 012001 (2020). [CrossRef]  

17. X. Chen, S. Chandrasekhar, S. Randel, G. Raybon, A. Adamiecki, P. Pupalaikis, and P. J. Winzer, “All-electronic 100-GHz bandwidth digital-to-analog converter generating PAM signals up to 190 GBaud,” J. Lightwave Technol. 35, 411–417 (2017). [CrossRef]  

18. V. J. Urick, J. D. McKinney, and K. J. Williams, Fundamentals of Microwave Photonics, Wiley Series in Microwave and Optical Engineering (Wiley, 2015).

19. R. W. Boyd, Nonlinear Optics (Elsevier, 2008).

20. K. Aoki, J. Kondou, O. Mitomi, and M. Minakata, “Velocity-matching conditions for ultrahigh-speed optical LiNbO3 modulators with traveling-wave electrode,” Jpn. J. Appl. Phys. 45, 8696–8698 (2006). [CrossRef]  

21. A. Rao and S. Fathpour, “Compact lithium niobate electrooptic modulators,” IEEE J. Sel. Top. Quantum Electron. 24, 3400114 (2018). [CrossRef]  

22. M. Doi, M. Sugiyama, K. Tanaka, and M. Kawai, “Advanced LiNbO3 optical modulators for broadband optical communications,” IEEE J. Sel. Top. Quantum Electron. 12, 745–750 (2006). [CrossRef]  

23. J. Shin, C. Ozturk, S. R. Sakamoto, Y. J. Chiu, and N. Dagli, “Novel T-rail electrodes for substrate removed low-voltage high-speed GaAs/AlGaAs electrooptic modulators,” IEEE Trans. Microw. Theory Tech. 53, 636–643 (2005). [CrossRef]  

24. J. Shin, S. R. Sakamoto, and N. Dagli, “Conductor loss of capacitively loaded slow wave electrodes for high-speed photonic devices,” J. Lightwave Technol. 29, 48–52 (2011). [CrossRef]  

25. R. Ding, Y. Liu, Y. Ma, Y. Yang, Q. Li, A. E. Lim, G. Lo, K. Bergman, T. Baehr-Jones, and M. Hochberg, “High-speed silicon modulator with slow-wave electrodes and fully independent differential drive,” J. Lightwave Technol. 32, 2240–2247 (2014). [CrossRef]  

26. G. Betts, “Velocity matching electrode structure for electro-optic modulators,” U.S. patent 6,310,700 (October 30, 2001).

27. X. Liu, B. Xiong, C. Sun, Z. Hao, L. Wang, J. Wang, Y. Han, H. Li, J. Yu, and Y. Luo, “Low half-wave-voltage thin film LiNbO3 electro-optic modulator based on a compact electrode structure,” in Asia Communications and Photonics Conference/International Conference on Information Photonics and Optical Communications (ACP/IPOC) (Optical Society of America, 2020), paper M4A.144.

28. R. G. Geyer and J. Krupka, “Microwave dielectric properties of anisotropic materials at cryogenic temperatures,” IEEE Trans. Instrum. Meas. 44, 329–331 (1995). [CrossRef]  

29. V. E. Stenger, J. Toney, A. Ponick, D. Brown, B. Griffin, R. Nelson, and S. Sriram, “Low loss and low VPI thin film lithium niobate on quartz electro-optic modulators,” in European Conference on Optical Communication (ECOC) (2017), pp. 1–3.

30. A. J. Mercante, S. Shi, P. Yao, L. Xie, R. M. Weikle, and D. W. Prather, “Thin film lithium niobate electro-optic modulator with terahertz operating bandwidth,” Opt. Express 26, 14810–14816 (2018). [CrossRef]  

31. G. L. Li, T. G. B. Mason, and P. K. L. Yu, “Analysis of segmented traveling-wave optical modulators,” J. Lightwave Technol. 22, 1789–1796 (2004). [CrossRef]  

32. M. Zhang, C. Wang, R. Cheng, A. Shams-Ansari, and M. Lončar, “Monolithic ultra-high-Q lithium niobate microring resonator,” Optica 4, 1536–1537 (2017). [CrossRef]  

33. S. Haxha, B. M. A. Rahman, and K. T. V. Grattan, “Bandwidth estimation for ultra-high-speed lithium niobate modulators,” Appl. Opt. 42, 2674–2682 (2003). [CrossRef]  

34. M. Lee, “Dielectric constant and loss tangent in LiNbO3 crystals from 90 to 147 GHz,” Appl. Phys. Lett. 79, 1342–1344 (2001). [CrossRef]  

35. L. He, M. Zhang, A. Shams-Ansari, R. Zhu, C. Wang, and L. Marko, “Low-loss fiber-to-chip interface for lithium niobate photonic integrated circuits,” Opt. Lett. 44, 2314–2317 (2019). [CrossRef]  

36. S. Kang, R. Zhang, Z. Hao, D. Jia, F. Gao, F. Bo, G. Zhang, and J. Xu, “High-efficiency chirped grating couplers on lithium niobate on insulator,” Opt. Lett. 45, 6651–6654 (2020). [CrossRef]  

37. A. Pan, C. Hu, C. Zeng, and J. Xia, “Fundamental mode hybridization in a thin film lithium niobate ridge waveguide,” Opt. Express 27, 35659–35669 (2019). [CrossRef]  

38. K. Suzuki, G. Cong, K. Tanizawa, S.-H. Kim, K. Ikeda, S. Namiki, and H. Kawashima, “Ultra-high-extinction-ratio 2 × 2 silicon optical switch with variable splitter,” Opt. Express 23, 9086–9092 (2015). [CrossRef]  

39. R. Nagarajan, “Technique for measuring the VPI-AC of a Mach-Zehnder modulator,” U.S. patent 6,204,954 (September 22, 1999).

40. Thorlabs, Lithium Niobate Electro-Optic Modulators, Fiber-Coupled (2020).

41. Fujitsu, Low Drive Voltage 40 Gb/s NRZ LiNBO3 External Modulator (2020).

42. K. Ashida, M. Okano, T. Yasuda, M. Ohtsuka, M. Seki, N. Yokoyama, K. Koshino, K. Yamada, and Y. Takahashi, “Photonic crystal nanocavities with an average Q factor of 1.9 million fabricated on a 300-mm-wide SOI wafer using a CMOS-compatible process,” J. Lightwave Technol. 36, 4774–4782 (2018). [CrossRef]  

43. A. F. Harvey, “Periodic and guiding structures at microwave frequencies,” IRE Trans. Microw. Theory Tech. 8, 30–61 (1960). [CrossRef]  

44. M. Y. Frankel, S. Gupta, J. A. Valdmanis, and G. A. Mourou, “Terahertz attenuation and dispersion characteristics of coplanar transmission lines,” IEEE Trans. Microw. Theory Tech. 39, 910–916 (1991). [CrossRef]  

45. K. Li, S. Liu, D. J. Thomson, W. Zhang, X. Yan, F. Meng, C. G. Littlejohns, H. Du, M. Banakar, M. Ebert, W. Cao, D. Tran, B. Chen, A. Shakoor, P. Petropoulos, and G. T. Reed, “Electronic-photonic convergence for silicon photonics transmitters beyond 100 Gbps on-off keying,” Optica 7, 1514–1516 (2020). [CrossRef]  

References

  • View by:

  1. E. Wooten, K. Kissa, A. Yi-Yan, E. Murphy, D. Lafaw, P. Hallemeier, D. Maack, D. Attanasio, D. Fritz, G. McBrien, and D. Bossi, “A review of lithium niobate modulators for fiber-optic communications systems,” IEEE J. Sel. Top. Quantum Electron. 6, 69–82 (2000).
    [Crossref]
  2. J. Zhou, J. Wang, L. Zhu, Q. Zhang, Q. Zhang, and J. Hong, “Silicon photonics carrier depletion modulators capable of 85Gbaud 16QAM and 64Gbaud 64QAM,” in Optical Fiber Communication Conference (Optical Society of America, 2019), paper Tu2H.2.
  3. M. Li, L. Wang, X. Li, X. Xiao, and S. Yu, “Silicon intensity Mach-Zehnder modulator for single lane 100 Gb/s applications,” Photon. Res. 6, 109–116 (2018).
    [Crossref]
  4. Y. Ogiso, J. Ozaki, Y. Ueda, H. Wakita, M. Nagatani, H. Yamazaki, M. Nakamura, T. Kobayashi, S. Kanazawa, Y. Hashizume, H. Tanobe, N. Nunoya, M. Ida, Y. Miyamoto, and M. Ishikawa, “80-GHz bandwidth and 1.5-v VPI InP-based IQ modulator,” J. Lightwave Technol. 38, 249–255 (2020).
    [Crossref]
  5. S. Dogru and N. Dagli, “0.77-V drive voltage electro-optic modulator with bandwidth exceeding 67 GHz,” Opt. Lett. 39, 6074–6077 (2014).
    [Crossref]
  6. P. Bhasker, J. Norman, J. Bowers, and N. Dagli, “Low voltage, high optical power handling capable, bulk compound semiconductor electro-optic modulators at 1550 nm,” J. Lightwave Technol. 38, 2308–2314 (2020).
    [Crossref]
  7. C. Kieninger, Y. Kutuvantavida, D. L. Elder, S. Wolf, H. Zwickel, M. Blaicher, J. N. Kemal, M. Lauermann, S. Randel, W. Freude, L. R. Dalton, and C. Koos, “Ultra-high electro-optic activity demonstrated in a silicon-organic hybrid modulator,” Optica 5, 739–748 (2018).
    [Crossref]
  8. C. Kieninger, Y. Kutuvantavida, H. Miura, J. N. Kemal, H. Zwickel, F. Qiu, M. Lauermann, W. Freude, S. Randel, S. Yokoyama, and C. Koos, “Demonstration of long-term thermally stable silicon-organic hybrid modulators at 85c,” Opt. Express 26, 27955–27964 (2018).
    [Crossref]
  9. M. Burla, C. Hoessbacher, W. Heni, C. Haffner, Y. Fedoryshyn, D. Werner, T. Watanabe, H. Massler, D. L. Elder, L. R. Dalton, and J. Leuthold, “500 GHz plasmonic Mach-Zehnder modulator enabling sub-THz microwave photonics,” APL Photon. 4, 056106 (2019).
    [Crossref]
  10. C. Wang, M. Zhang, X. Chen, M. Bertrand, A. Shams-Ansari, S. Chandrasekhar, P. Winzer, and M. Loncar, “Integrated lithium niobate electro-optic modulators operating at CMOS-compatible voltages,” Nature 562, 101–104 (2018).
    [Crossref]
  11. M. Xu, M. He, H. Zhang, J. Jian, Y. Pan, X. Liu, L. Chen, X. Meng, H. Chen, Z. Li, X. Xiao, S. Yu, S. Yu, and X. Cai, “High-performance coherent optical modulators based on thin-film lithium niobate platform,” Nat. Commun. 11, 3911 (2020).
    [Crossref]
  12. A. N. R. Ahmed, S. Shi, A. Mercante, S. Nelan, P. Yao, and D. W. Prather, “High-efficiency lithium niobate modulator for K band operation,” APL Photon. 5, 091302 (2020).
    [Crossref]
  13. A. Honardoost, F. A. Juneghani, R. Safian, and S. Fathpour, “Towards subterahertz bandwidth ultracompact lithium niobate electrooptic modulators,” Opt. Express 27, 6495–6501 (2019).
    [Crossref]
  14. A. Honardoost, R. Safian, A. Rao, and S. Fathpour, “High-speed modeling of ultracompact electrooptic modulators,” J. Lightwave Technol. 36, 5893–5902 (2018).
    [Crossref]
  15. R. Safian, M. Teng, L. Zhuang, and S. Chakravarty, “Foundry-compatible thin film lithium niobate modulator with RF electrodes buried inside the silicon oxide layer of the SOI wafer,” Opt. Express 28, 25843–25857 (2020).
    [Crossref]
  16. W. Peter Orlando, V. Forrest, Z. Jie, L. Huiyan, and M. Shayan, “Design of high-bandwidth, low-voltage and low-loss hybrid lithium niobate electro-optic modulators,” J. Phys. Photon. 3, 012001 (2020).
    [Crossref]
  17. X. Chen, S. Chandrasekhar, S. Randel, G. Raybon, A. Adamiecki, P. Pupalaikis, and P. J. Winzer, “All-electronic 100-GHz bandwidth digital-to-analog converter generating PAM signals up to 190 GBaud,” J. Lightwave Technol. 35, 411–417 (2017).
    [Crossref]
  18. V. J. Urick, J. D. McKinney, and K. J. Williams, Fundamentals of Microwave Photonics, Wiley Series in Microwave and Optical Engineering (Wiley, 2015).
  19. R. W. Boyd, Nonlinear Optics (Elsevier, 2008).
  20. K. Aoki, J. Kondou, O. Mitomi, and M. Minakata, “Velocity-matching conditions for ultrahigh-speed optical LiNbO3 modulators with traveling-wave electrode,” Jpn. J. Appl. Phys. 45, 8696–8698 (2006).
    [Crossref]
  21. A. Rao and S. Fathpour, “Compact lithium niobate electrooptic modulators,” IEEE J. Sel. Top. Quantum Electron. 24, 3400114 (2018).
    [Crossref]
  22. M. Doi, M. Sugiyama, K. Tanaka, and M. Kawai, “Advanced LiNbO3 optical modulators for broadband optical communications,” IEEE J. Sel. Top. Quantum Electron. 12, 745–750 (2006).
    [Crossref]
  23. J. Shin, C. Ozturk, S. R. Sakamoto, Y. J. Chiu, and N. Dagli, “Novel T-rail electrodes for substrate removed low-voltage high-speed GaAs/AlGaAs electrooptic modulators,” IEEE Trans. Microw. Theory Tech. 53, 636–643 (2005).
    [Crossref]
  24. J. Shin, S. R. Sakamoto, and N. Dagli, “Conductor loss of capacitively loaded slow wave electrodes for high-speed photonic devices,” J. Lightwave Technol. 29, 48–52 (2011).
    [Crossref]
  25. R. Ding, Y. Liu, Y. Ma, Y. Yang, Q. Li, A. E. Lim, G. Lo, K. Bergman, T. Baehr-Jones, and M. Hochberg, “High-speed silicon modulator with slow-wave electrodes and fully independent differential drive,” J. Lightwave Technol. 32, 2240–2247 (2014).
    [Crossref]
  26. G. Betts, “Velocity matching electrode structure for electro-optic modulators,” U.S. patent6,310,700 (October30, 2001).
  27. X. Liu, B. Xiong, C. Sun, Z. Hao, L. Wang, J. Wang, Y. Han, H. Li, J. Yu, and Y. Luo, “Low half-wave-voltage thin film LiNbO3 electro-optic modulator based on a compact electrode structure,” in Asia Communications and Photonics Conference/International Conference on Information Photonics and Optical Communications (ACP/IPOC) (Optical Society of America, 2020), paper M4A.144.
  28. R. G. Geyer and J. Krupka, “Microwave dielectric properties of anisotropic materials at cryogenic temperatures,” IEEE Trans. Instrum. Meas. 44, 329–331 (1995).
    [Crossref]
  29. V. E. Stenger, J. Toney, A. Ponick, D. Brown, B. Griffin, R. Nelson, and S. Sriram, “Low loss and low VPI thin film lithium niobate on quartz electro-optic modulators,” in European Conference on Optical Communication (ECOC) (2017), pp. 1–3.
  30. A. J. Mercante, S. Shi, P. Yao, L. Xie, R. M. Weikle, and D. W. Prather, “Thin film lithium niobate electro-optic modulator with terahertz operating bandwidth,” Opt. Express 26, 14810–14816 (2018).
    [Crossref]
  31. G. L. Li, T. G. B. Mason, and P. K. L. Yu, “Analysis of segmented traveling-wave optical modulators,” J. Lightwave Technol. 22, 1789–1796 (2004).
    [Crossref]
  32. M. Zhang, C. Wang, R. Cheng, A. Shams-Ansari, and M. Lončar, “Monolithic ultra-high-Q lithium niobate microring resonator,” Optica 4, 1536–1537 (2017).
    [Crossref]
  33. S. Haxha, B. M. A. Rahman, and K. T. V. Grattan, “Bandwidth estimation for ultra-high-speed lithium niobate modulators,” Appl. Opt. 42, 2674–2682 (2003).
    [Crossref]
  34. M. Lee, “Dielectric constant and loss tangent in LiNbO3 crystals from 90 to 147 GHz,” Appl. Phys. Lett. 79, 1342–1344 (2001).
    [Crossref]
  35. L. He, M. Zhang, A. Shams-Ansari, R. Zhu, C. Wang, and L. Marko, “Low-loss fiber-to-chip interface for lithium niobate photonic integrated circuits,” Opt. Lett. 44, 2314–2317 (2019).
    [Crossref]
  36. S. Kang, R. Zhang, Z. Hao, D. Jia, F. Gao, F. Bo, G. Zhang, and J. Xu, “High-efficiency chirped grating couplers on lithium niobate on insulator,” Opt. Lett. 45, 6651–6654 (2020).
    [Crossref]
  37. A. Pan, C. Hu, C. Zeng, and J. Xia, “Fundamental mode hybridization in a thin film lithium niobate ridge waveguide,” Opt. Express 27, 35659–35669 (2019).
    [Crossref]
  38. K. Suzuki, G. Cong, K. Tanizawa, S.-H. Kim, K. Ikeda, S. Namiki, and H. Kawashima, “Ultra-high-extinction-ratio 2 × 2 silicon optical switch with variable splitter,” Opt. Express 23, 9086–9092 (2015).
    [Crossref]
  39. R. Nagarajan, “Technique for measuring the VPI-AC of a Mach-Zehnder modulator,” U.S. patent6,204,954 (September22, 1999).
  40. Thorlabs, Lithium Niobate Electro-Optic Modulators, Fiber-Coupled (2020).
  41. Fujitsu, Low Drive Voltage 40 Gb/s NRZ LiNBO3 External Modulator (2020).
  42. K. Ashida, M. Okano, T. Yasuda, M. Ohtsuka, M. Seki, N. Yokoyama, K. Koshino, K. Yamada, and Y. Takahashi, “Photonic crystal nanocavities with an average Q factor of 1.9 million fabricated on a 300-mm-wide SOI wafer using a CMOS-compatible process,” J. Lightwave Technol. 36, 4774–4782 (2018).
    [Crossref]
  43. A. F. Harvey, “Periodic and guiding structures at microwave frequencies,” IRE Trans. Microw. Theory Tech. 8, 30–61 (1960).
    [Crossref]
  44. M. Y. Frankel, S. Gupta, J. A. Valdmanis, and G. A. Mourou, “Terahertz attenuation and dispersion characteristics of coplanar transmission lines,” IEEE Trans. Microw. Theory Tech. 39, 910–916 (1991).
    [Crossref]
  45. K. Li, S. Liu, D. J. Thomson, W. Zhang, X. Yan, F. Meng, C. G. Littlejohns, H. Du, M. Banakar, M. Ebert, W. Cao, D. Tran, B. Chen, A. Shakoor, P. Petropoulos, and G. T. Reed, “Electronic-photonic convergence for silicon photonics transmitters beyond 100 Gbps on-off keying,” Optica 7, 1514–1516 (2020).
    [Crossref]

2020 (8)

Y. Ogiso, J. Ozaki, Y. Ueda, H. Wakita, M. Nagatani, H. Yamazaki, M. Nakamura, T. Kobayashi, S. Kanazawa, Y. Hashizume, H. Tanobe, N. Nunoya, M. Ida, Y. Miyamoto, and M. Ishikawa, “80-GHz bandwidth and 1.5-v VPI InP-based IQ modulator,” J. Lightwave Technol. 38, 249–255 (2020).
[Crossref]

P. Bhasker, J. Norman, J. Bowers, and N. Dagli, “Low voltage, high optical power handling capable, bulk compound semiconductor electro-optic modulators at 1550 nm,” J. Lightwave Technol. 38, 2308–2314 (2020).
[Crossref]

M. Xu, M. He, H. Zhang, J. Jian, Y. Pan, X. Liu, L. Chen, X. Meng, H. Chen, Z. Li, X. Xiao, S. Yu, S. Yu, and X. Cai, “High-performance coherent optical modulators based on thin-film lithium niobate platform,” Nat. Commun. 11, 3911 (2020).
[Crossref]

A. N. R. Ahmed, S. Shi, A. Mercante, S. Nelan, P. Yao, and D. W. Prather, “High-efficiency lithium niobate modulator for K band operation,” APL Photon. 5, 091302 (2020).
[Crossref]

R. Safian, M. Teng, L. Zhuang, and S. Chakravarty, “Foundry-compatible thin film lithium niobate modulator with RF electrodes buried inside the silicon oxide layer of the SOI wafer,” Opt. Express 28, 25843–25857 (2020).
[Crossref]

W. Peter Orlando, V. Forrest, Z. Jie, L. Huiyan, and M. Shayan, “Design of high-bandwidth, low-voltage and low-loss hybrid lithium niobate electro-optic modulators,” J. Phys. Photon. 3, 012001 (2020).
[Crossref]

S. Kang, R. Zhang, Z. Hao, D. Jia, F. Gao, F. Bo, G. Zhang, and J. Xu, “High-efficiency chirped grating couplers on lithium niobate on insulator,” Opt. Lett. 45, 6651–6654 (2020).
[Crossref]

K. Li, S. Liu, D. J. Thomson, W. Zhang, X. Yan, F. Meng, C. G. Littlejohns, H. Du, M. Banakar, M. Ebert, W. Cao, D. Tran, B. Chen, A. Shakoor, P. Petropoulos, and G. T. Reed, “Electronic-photonic convergence for silicon photonics transmitters beyond 100 Gbps on-off keying,” Optica 7, 1514–1516 (2020).
[Crossref]

2019 (4)

2018 (8)

C. Wang, M. Zhang, X. Chen, M. Bertrand, A. Shams-Ansari, S. Chandrasekhar, P. Winzer, and M. Loncar, “Integrated lithium niobate electro-optic modulators operating at CMOS-compatible voltages,” Nature 562, 101–104 (2018).
[Crossref]

C. Kieninger, Y. Kutuvantavida, D. L. Elder, S. Wolf, H. Zwickel, M. Blaicher, J. N. Kemal, M. Lauermann, S. Randel, W. Freude, L. R. Dalton, and C. Koos, “Ultra-high electro-optic activity demonstrated in a silicon-organic hybrid modulator,” Optica 5, 739–748 (2018).
[Crossref]

C. Kieninger, Y. Kutuvantavida, H. Miura, J. N. Kemal, H. Zwickel, F. Qiu, M. Lauermann, W. Freude, S. Randel, S. Yokoyama, and C. Koos, “Demonstration of long-term thermally stable silicon-organic hybrid modulators at 85c,” Opt. Express 26, 27955–27964 (2018).
[Crossref]

M. Li, L. Wang, X. Li, X. Xiao, and S. Yu, “Silicon intensity Mach-Zehnder modulator for single lane 100 Gb/s applications,” Photon. Res. 6, 109–116 (2018).
[Crossref]

A. Honardoost, R. Safian, A. Rao, and S. Fathpour, “High-speed modeling of ultracompact electrooptic modulators,” J. Lightwave Technol. 36, 5893–5902 (2018).
[Crossref]

K. Ashida, M. Okano, T. Yasuda, M. Ohtsuka, M. Seki, N. Yokoyama, K. Koshino, K. Yamada, and Y. Takahashi, “Photonic crystal nanocavities with an average Q factor of 1.9 million fabricated on a 300-mm-wide SOI wafer using a CMOS-compatible process,” J. Lightwave Technol. 36, 4774–4782 (2018).
[Crossref]

A. Rao and S. Fathpour, “Compact lithium niobate electrooptic modulators,” IEEE J. Sel. Top. Quantum Electron. 24, 3400114 (2018).
[Crossref]

A. J. Mercante, S. Shi, P. Yao, L. Xie, R. M. Weikle, and D. W. Prather, “Thin film lithium niobate electro-optic modulator with terahertz operating bandwidth,” Opt. Express 26, 14810–14816 (2018).
[Crossref]

2017 (2)

2015 (1)

2014 (2)

2011 (1)

2006 (2)

M. Doi, M. Sugiyama, K. Tanaka, and M. Kawai, “Advanced LiNbO3 optical modulators for broadband optical communications,” IEEE J. Sel. Top. Quantum Electron. 12, 745–750 (2006).
[Crossref]

K. Aoki, J. Kondou, O. Mitomi, and M. Minakata, “Velocity-matching conditions for ultrahigh-speed optical LiNbO3 modulators with traveling-wave electrode,” Jpn. J. Appl. Phys. 45, 8696–8698 (2006).
[Crossref]

2005 (1)

J. Shin, C. Ozturk, S. R. Sakamoto, Y. J. Chiu, and N. Dagli, “Novel T-rail electrodes for substrate removed low-voltage high-speed GaAs/AlGaAs electrooptic modulators,” IEEE Trans. Microw. Theory Tech. 53, 636–643 (2005).
[Crossref]

2004 (1)

2003 (1)

2001 (1)

M. Lee, “Dielectric constant and loss tangent in LiNbO3 crystals from 90 to 147 GHz,” Appl. Phys. Lett. 79, 1342–1344 (2001).
[Crossref]

2000 (1)

E. Wooten, K. Kissa, A. Yi-Yan, E. Murphy, D. Lafaw, P. Hallemeier, D. Maack, D. Attanasio, D. Fritz, G. McBrien, and D. Bossi, “A review of lithium niobate modulators for fiber-optic communications systems,” IEEE J. Sel. Top. Quantum Electron. 6, 69–82 (2000).
[Crossref]

1995 (1)

R. G. Geyer and J. Krupka, “Microwave dielectric properties of anisotropic materials at cryogenic temperatures,” IEEE Trans. Instrum. Meas. 44, 329–331 (1995).
[Crossref]

1991 (1)

M. Y. Frankel, S. Gupta, J. A. Valdmanis, and G. A. Mourou, “Terahertz attenuation and dispersion characteristics of coplanar transmission lines,” IEEE Trans. Microw. Theory Tech. 39, 910–916 (1991).
[Crossref]

1960 (1)

A. F. Harvey, “Periodic and guiding structures at microwave frequencies,” IRE Trans. Microw. Theory Tech. 8, 30–61 (1960).
[Crossref]

Adamiecki, A.

Ahmed, A. N. R.

A. N. R. Ahmed, S. Shi, A. Mercante, S. Nelan, P. Yao, and D. W. Prather, “High-efficiency lithium niobate modulator for K band operation,” APL Photon. 5, 091302 (2020).
[Crossref]

Aoki, K.

K. Aoki, J. Kondou, O. Mitomi, and M. Minakata, “Velocity-matching conditions for ultrahigh-speed optical LiNbO3 modulators with traveling-wave electrode,” Jpn. J. Appl. Phys. 45, 8696–8698 (2006).
[Crossref]

Ashida, K.

Attanasio, D.

E. Wooten, K. Kissa, A. Yi-Yan, E. Murphy, D. Lafaw, P. Hallemeier, D. Maack, D. Attanasio, D. Fritz, G. McBrien, and D. Bossi, “A review of lithium niobate modulators for fiber-optic communications systems,” IEEE J. Sel. Top. Quantum Electron. 6, 69–82 (2000).
[Crossref]

Baehr-Jones, T.

Banakar, M.

Bergman, K.

Bertrand, M.

C. Wang, M. Zhang, X. Chen, M. Bertrand, A. Shams-Ansari, S. Chandrasekhar, P. Winzer, and M. Loncar, “Integrated lithium niobate electro-optic modulators operating at CMOS-compatible voltages,” Nature 562, 101–104 (2018).
[Crossref]

Betts, G.

G. Betts, “Velocity matching electrode structure for electro-optic modulators,” U.S. patent6,310,700 (October30, 2001).

Bhasker, P.

Blaicher, M.

Bo, F.

Bossi, D.

E. Wooten, K. Kissa, A. Yi-Yan, E. Murphy, D. Lafaw, P. Hallemeier, D. Maack, D. Attanasio, D. Fritz, G. McBrien, and D. Bossi, “A review of lithium niobate modulators for fiber-optic communications systems,” IEEE J. Sel. Top. Quantum Electron. 6, 69–82 (2000).
[Crossref]

Bowers, J.

Boyd, R. W.

R. W. Boyd, Nonlinear Optics (Elsevier, 2008).

Brown, D.

V. E. Stenger, J. Toney, A. Ponick, D. Brown, B. Griffin, R. Nelson, and S. Sriram, “Low loss and low VPI thin film lithium niobate on quartz electro-optic modulators,” in European Conference on Optical Communication (ECOC) (2017), pp. 1–3.

Burla, M.

M. Burla, C. Hoessbacher, W. Heni, C. Haffner, Y. Fedoryshyn, D. Werner, T. Watanabe, H. Massler, D. L. Elder, L. R. Dalton, and J. Leuthold, “500 GHz plasmonic Mach-Zehnder modulator enabling sub-THz microwave photonics,” APL Photon. 4, 056106 (2019).
[Crossref]

Cai, X.

M. Xu, M. He, H. Zhang, J. Jian, Y. Pan, X. Liu, L. Chen, X. Meng, H. Chen, Z. Li, X. Xiao, S. Yu, S. Yu, and X. Cai, “High-performance coherent optical modulators based on thin-film lithium niobate platform,” Nat. Commun. 11, 3911 (2020).
[Crossref]

Cao, W.

Chakravarty, S.

Chandrasekhar, S.

C. Wang, M. Zhang, X. Chen, M. Bertrand, A. Shams-Ansari, S. Chandrasekhar, P. Winzer, and M. Loncar, “Integrated lithium niobate electro-optic modulators operating at CMOS-compatible voltages,” Nature 562, 101–104 (2018).
[Crossref]

X. Chen, S. Chandrasekhar, S. Randel, G. Raybon, A. Adamiecki, P. Pupalaikis, and P. J. Winzer, “All-electronic 100-GHz bandwidth digital-to-analog converter generating PAM signals up to 190 GBaud,” J. Lightwave Technol. 35, 411–417 (2017).
[Crossref]

Chen, B.

Chen, H.

M. Xu, M. He, H. Zhang, J. Jian, Y. Pan, X. Liu, L. Chen, X. Meng, H. Chen, Z. Li, X. Xiao, S. Yu, S. Yu, and X. Cai, “High-performance coherent optical modulators based on thin-film lithium niobate platform,” Nat. Commun. 11, 3911 (2020).
[Crossref]

Chen, L.

M. Xu, M. He, H. Zhang, J. Jian, Y. Pan, X. Liu, L. Chen, X. Meng, H. Chen, Z. Li, X. Xiao, S. Yu, S. Yu, and X. Cai, “High-performance coherent optical modulators based on thin-film lithium niobate platform,” Nat. Commun. 11, 3911 (2020).
[Crossref]

Chen, X.

C. Wang, M. Zhang, X. Chen, M. Bertrand, A. Shams-Ansari, S. Chandrasekhar, P. Winzer, and M. Loncar, “Integrated lithium niobate electro-optic modulators operating at CMOS-compatible voltages,” Nature 562, 101–104 (2018).
[Crossref]

X. Chen, S. Chandrasekhar, S. Randel, G. Raybon, A. Adamiecki, P. Pupalaikis, and P. J. Winzer, “All-electronic 100-GHz bandwidth digital-to-analog converter generating PAM signals up to 190 GBaud,” J. Lightwave Technol. 35, 411–417 (2017).
[Crossref]

Cheng, R.

Chiu, Y. J.

J. Shin, C. Ozturk, S. R. Sakamoto, Y. J. Chiu, and N. Dagli, “Novel T-rail electrodes for substrate removed low-voltage high-speed GaAs/AlGaAs electrooptic modulators,” IEEE Trans. Microw. Theory Tech. 53, 636–643 (2005).
[Crossref]

Cong, G.

Dagli, N.

Dalton, L. R.

M. Burla, C. Hoessbacher, W. Heni, C. Haffner, Y. Fedoryshyn, D. Werner, T. Watanabe, H. Massler, D. L. Elder, L. R. Dalton, and J. Leuthold, “500 GHz plasmonic Mach-Zehnder modulator enabling sub-THz microwave photonics,” APL Photon. 4, 056106 (2019).
[Crossref]

C. Kieninger, Y. Kutuvantavida, D. L. Elder, S. Wolf, H. Zwickel, M. Blaicher, J. N. Kemal, M. Lauermann, S. Randel, W. Freude, L. R. Dalton, and C. Koos, “Ultra-high electro-optic activity demonstrated in a silicon-organic hybrid modulator,” Optica 5, 739–748 (2018).
[Crossref]

Ding, R.

Dogru, S.

Doi, M.

M. Doi, M. Sugiyama, K. Tanaka, and M. Kawai, “Advanced LiNbO3 optical modulators for broadband optical communications,” IEEE J. Sel. Top. Quantum Electron. 12, 745–750 (2006).
[Crossref]

Du, H.

Ebert, M.

Elder, D. L.

M. Burla, C. Hoessbacher, W. Heni, C. Haffner, Y. Fedoryshyn, D. Werner, T. Watanabe, H. Massler, D. L. Elder, L. R. Dalton, and J. Leuthold, “500 GHz plasmonic Mach-Zehnder modulator enabling sub-THz microwave photonics,” APL Photon. 4, 056106 (2019).
[Crossref]

C. Kieninger, Y. Kutuvantavida, D. L. Elder, S. Wolf, H. Zwickel, M. Blaicher, J. N. Kemal, M. Lauermann, S. Randel, W. Freude, L. R. Dalton, and C. Koos, “Ultra-high electro-optic activity demonstrated in a silicon-organic hybrid modulator,” Optica 5, 739–748 (2018).
[Crossref]

Fathpour, S.

Fedoryshyn, Y.

M. Burla, C. Hoessbacher, W. Heni, C. Haffner, Y. Fedoryshyn, D. Werner, T. Watanabe, H. Massler, D. L. Elder, L. R. Dalton, and J. Leuthold, “500 GHz plasmonic Mach-Zehnder modulator enabling sub-THz microwave photonics,” APL Photon. 4, 056106 (2019).
[Crossref]

Forrest, V.

W. Peter Orlando, V. Forrest, Z. Jie, L. Huiyan, and M. Shayan, “Design of high-bandwidth, low-voltage and low-loss hybrid lithium niobate electro-optic modulators,” J. Phys. Photon. 3, 012001 (2020).
[Crossref]

Frankel, M. Y.

M. Y. Frankel, S. Gupta, J. A. Valdmanis, and G. A. Mourou, “Terahertz attenuation and dispersion characteristics of coplanar transmission lines,” IEEE Trans. Microw. Theory Tech. 39, 910–916 (1991).
[Crossref]

Freude, W.

Fritz, D.

E. Wooten, K. Kissa, A. Yi-Yan, E. Murphy, D. Lafaw, P. Hallemeier, D. Maack, D. Attanasio, D. Fritz, G. McBrien, and D. Bossi, “A review of lithium niobate modulators for fiber-optic communications systems,” IEEE J. Sel. Top. Quantum Electron. 6, 69–82 (2000).
[Crossref]

Gao, F.

Geyer, R. G.

R. G. Geyer and J. Krupka, “Microwave dielectric properties of anisotropic materials at cryogenic temperatures,” IEEE Trans. Instrum. Meas. 44, 329–331 (1995).
[Crossref]

Grattan, K. T. V.

Griffin, B.

V. E. Stenger, J. Toney, A. Ponick, D. Brown, B. Griffin, R. Nelson, and S. Sriram, “Low loss and low VPI thin film lithium niobate on quartz electro-optic modulators,” in European Conference on Optical Communication (ECOC) (2017), pp. 1–3.

Gupta, S.

M. Y. Frankel, S. Gupta, J. A. Valdmanis, and G. A. Mourou, “Terahertz attenuation and dispersion characteristics of coplanar transmission lines,” IEEE Trans. Microw. Theory Tech. 39, 910–916 (1991).
[Crossref]

Haffner, C.

M. Burla, C. Hoessbacher, W. Heni, C. Haffner, Y. Fedoryshyn, D. Werner, T. Watanabe, H. Massler, D. L. Elder, L. R. Dalton, and J. Leuthold, “500 GHz plasmonic Mach-Zehnder modulator enabling sub-THz microwave photonics,” APL Photon. 4, 056106 (2019).
[Crossref]

Hallemeier, P.

E. Wooten, K. Kissa, A. Yi-Yan, E. Murphy, D. Lafaw, P. Hallemeier, D. Maack, D. Attanasio, D. Fritz, G. McBrien, and D. Bossi, “A review of lithium niobate modulators for fiber-optic communications systems,” IEEE J. Sel. Top. Quantum Electron. 6, 69–82 (2000).
[Crossref]

Han, Y.

X. Liu, B. Xiong, C. Sun, Z. Hao, L. Wang, J. Wang, Y. Han, H. Li, J. Yu, and Y. Luo, “Low half-wave-voltage thin film LiNbO3 electro-optic modulator based on a compact electrode structure,” in Asia Communications and Photonics Conference/International Conference on Information Photonics and Optical Communications (ACP/IPOC) (Optical Society of America, 2020), paper M4A.144.

Hao, Z.

S. Kang, R. Zhang, Z. Hao, D. Jia, F. Gao, F. Bo, G. Zhang, and J. Xu, “High-efficiency chirped grating couplers on lithium niobate on insulator,” Opt. Lett. 45, 6651–6654 (2020).
[Crossref]

X. Liu, B. Xiong, C. Sun, Z. Hao, L. Wang, J. Wang, Y. Han, H. Li, J. Yu, and Y. Luo, “Low half-wave-voltage thin film LiNbO3 electro-optic modulator based on a compact electrode structure,” in Asia Communications and Photonics Conference/International Conference on Information Photonics and Optical Communications (ACP/IPOC) (Optical Society of America, 2020), paper M4A.144.

Harvey, A. F.

A. F. Harvey, “Periodic and guiding structures at microwave frequencies,” IRE Trans. Microw. Theory Tech. 8, 30–61 (1960).
[Crossref]

Hashizume, Y.

Haxha, S.

He, L.

He, M.

M. Xu, M. He, H. Zhang, J. Jian, Y. Pan, X. Liu, L. Chen, X. Meng, H. Chen, Z. Li, X. Xiao, S. Yu, S. Yu, and X. Cai, “High-performance coherent optical modulators based on thin-film lithium niobate platform,” Nat. Commun. 11, 3911 (2020).
[Crossref]

Heni, W.

M. Burla, C. Hoessbacher, W. Heni, C. Haffner, Y. Fedoryshyn, D. Werner, T. Watanabe, H. Massler, D. L. Elder, L. R. Dalton, and J. Leuthold, “500 GHz plasmonic Mach-Zehnder modulator enabling sub-THz microwave photonics,” APL Photon. 4, 056106 (2019).
[Crossref]

Hochberg, M.

Hoessbacher, C.

M. Burla, C. Hoessbacher, W. Heni, C. Haffner, Y. Fedoryshyn, D. Werner, T. Watanabe, H. Massler, D. L. Elder, L. R. Dalton, and J. Leuthold, “500 GHz plasmonic Mach-Zehnder modulator enabling sub-THz microwave photonics,” APL Photon. 4, 056106 (2019).
[Crossref]

Honardoost, A.

Hong, J.

J. Zhou, J. Wang, L. Zhu, Q. Zhang, Q. Zhang, and J. Hong, “Silicon photonics carrier depletion modulators capable of 85Gbaud 16QAM and 64Gbaud 64QAM,” in Optical Fiber Communication Conference (Optical Society of America, 2019), paper Tu2H.2.

Hu, C.

Huiyan, L.

W. Peter Orlando, V. Forrest, Z. Jie, L. Huiyan, and M. Shayan, “Design of high-bandwidth, low-voltage and low-loss hybrid lithium niobate electro-optic modulators,” J. Phys. Photon. 3, 012001 (2020).
[Crossref]

Ida, M.

Ikeda, K.

Ishikawa, M.

Jia, D.

Jian, J.

M. Xu, M. He, H. Zhang, J. Jian, Y. Pan, X. Liu, L. Chen, X. Meng, H. Chen, Z. Li, X. Xiao, S. Yu, S. Yu, and X. Cai, “High-performance coherent optical modulators based on thin-film lithium niobate platform,” Nat. Commun. 11, 3911 (2020).
[Crossref]

Jie, Z.

W. Peter Orlando, V. Forrest, Z. Jie, L. Huiyan, and M. Shayan, “Design of high-bandwidth, low-voltage and low-loss hybrid lithium niobate electro-optic modulators,” J. Phys. Photon. 3, 012001 (2020).
[Crossref]

Juneghani, F. A.

Kanazawa, S.

Kang, S.

Kawai, M.

M. Doi, M. Sugiyama, K. Tanaka, and M. Kawai, “Advanced LiNbO3 optical modulators for broadband optical communications,” IEEE J. Sel. Top. Quantum Electron. 12, 745–750 (2006).
[Crossref]

Kawashima, H.

Kemal, J. N.

Kieninger, C.

Kim, S.-H.

Kissa, K.

E. Wooten, K. Kissa, A. Yi-Yan, E. Murphy, D. Lafaw, P. Hallemeier, D. Maack, D. Attanasio, D. Fritz, G. McBrien, and D. Bossi, “A review of lithium niobate modulators for fiber-optic communications systems,” IEEE J. Sel. Top. Quantum Electron. 6, 69–82 (2000).
[Crossref]

Kobayashi, T.

Kondou, J.

K. Aoki, J. Kondou, O. Mitomi, and M. Minakata, “Velocity-matching conditions for ultrahigh-speed optical LiNbO3 modulators with traveling-wave electrode,” Jpn. J. Appl. Phys. 45, 8696–8698 (2006).
[Crossref]

Koos, C.

Koshino, K.

Krupka, J.

R. G. Geyer and J. Krupka, “Microwave dielectric properties of anisotropic materials at cryogenic temperatures,” IEEE Trans. Instrum. Meas. 44, 329–331 (1995).
[Crossref]

Kutuvantavida, Y.

Lafaw, D.

E. Wooten, K. Kissa, A. Yi-Yan, E. Murphy, D. Lafaw, P. Hallemeier, D. Maack, D. Attanasio, D. Fritz, G. McBrien, and D. Bossi, “A review of lithium niobate modulators for fiber-optic communications systems,” IEEE J. Sel. Top. Quantum Electron. 6, 69–82 (2000).
[Crossref]

Lauermann, M.

Lee, M.

M. Lee, “Dielectric constant and loss tangent in LiNbO3 crystals from 90 to 147 GHz,” Appl. Phys. Lett. 79, 1342–1344 (2001).
[Crossref]

Leuthold, J.

M. Burla, C. Hoessbacher, W. Heni, C. Haffner, Y. Fedoryshyn, D. Werner, T. Watanabe, H. Massler, D. L. Elder, L. R. Dalton, and J. Leuthold, “500 GHz plasmonic Mach-Zehnder modulator enabling sub-THz microwave photonics,” APL Photon. 4, 056106 (2019).
[Crossref]

Li, G. L.

Li, H.

X. Liu, B. Xiong, C. Sun, Z. Hao, L. Wang, J. Wang, Y. Han, H. Li, J. Yu, and Y. Luo, “Low half-wave-voltage thin film LiNbO3 electro-optic modulator based on a compact electrode structure,” in Asia Communications and Photonics Conference/International Conference on Information Photonics and Optical Communications (ACP/IPOC) (Optical Society of America, 2020), paper M4A.144.

Li, K.

Li, M.

Li, Q.

Li, X.

Li, Z.

M. Xu, M. He, H. Zhang, J. Jian, Y. Pan, X. Liu, L. Chen, X. Meng, H. Chen, Z. Li, X. Xiao, S. Yu, S. Yu, and X. Cai, “High-performance coherent optical modulators based on thin-film lithium niobate platform,” Nat. Commun. 11, 3911 (2020).
[Crossref]

Lim, A. E.

Littlejohns, C. G.

Liu, S.

Liu, X.

M. Xu, M. He, H. Zhang, J. Jian, Y. Pan, X. Liu, L. Chen, X. Meng, H. Chen, Z. Li, X. Xiao, S. Yu, S. Yu, and X. Cai, “High-performance coherent optical modulators based on thin-film lithium niobate platform,” Nat. Commun. 11, 3911 (2020).
[Crossref]

X. Liu, B. Xiong, C. Sun, Z. Hao, L. Wang, J. Wang, Y. Han, H. Li, J. Yu, and Y. Luo, “Low half-wave-voltage thin film LiNbO3 electro-optic modulator based on a compact electrode structure,” in Asia Communications and Photonics Conference/International Conference on Information Photonics and Optical Communications (ACP/IPOC) (Optical Society of America, 2020), paper M4A.144.

Liu, Y.

Lo, G.

Loncar, M.

C. Wang, M. Zhang, X. Chen, M. Bertrand, A. Shams-Ansari, S. Chandrasekhar, P. Winzer, and M. Loncar, “Integrated lithium niobate electro-optic modulators operating at CMOS-compatible voltages,” Nature 562, 101–104 (2018).
[Crossref]

M. Zhang, C. Wang, R. Cheng, A. Shams-Ansari, and M. Lončar, “Monolithic ultra-high-Q lithium niobate microring resonator,” Optica 4, 1536–1537 (2017).
[Crossref]

Luo, Y.

X. Liu, B. Xiong, C. Sun, Z. Hao, L. Wang, J. Wang, Y. Han, H. Li, J. Yu, and Y. Luo, “Low half-wave-voltage thin film LiNbO3 electro-optic modulator based on a compact electrode structure,” in Asia Communications and Photonics Conference/International Conference on Information Photonics and Optical Communications (ACP/IPOC) (Optical Society of America, 2020), paper M4A.144.

Ma, Y.

Maack, D.

E. Wooten, K. Kissa, A. Yi-Yan, E. Murphy, D. Lafaw, P. Hallemeier, D. Maack, D. Attanasio, D. Fritz, G. McBrien, and D. Bossi, “A review of lithium niobate modulators for fiber-optic communications systems,” IEEE J. Sel. Top. Quantum Electron. 6, 69–82 (2000).
[Crossref]

Marko, L.

Mason, T. G. B.

Massler, H.

M. Burla, C. Hoessbacher, W. Heni, C. Haffner, Y. Fedoryshyn, D. Werner, T. Watanabe, H. Massler, D. L. Elder, L. R. Dalton, and J. Leuthold, “500 GHz plasmonic Mach-Zehnder modulator enabling sub-THz microwave photonics,” APL Photon. 4, 056106 (2019).
[Crossref]

McBrien, G.

E. Wooten, K. Kissa, A. Yi-Yan, E. Murphy, D. Lafaw, P. Hallemeier, D. Maack, D. Attanasio, D. Fritz, G. McBrien, and D. Bossi, “A review of lithium niobate modulators for fiber-optic communications systems,” IEEE J. Sel. Top. Quantum Electron. 6, 69–82 (2000).
[Crossref]

McKinney, J. D.

V. J. Urick, J. D. McKinney, and K. J. Williams, Fundamentals of Microwave Photonics, Wiley Series in Microwave and Optical Engineering (Wiley, 2015).

Meng, F.

Meng, X.

M. Xu, M. He, H. Zhang, J. Jian, Y. Pan, X. Liu, L. Chen, X. Meng, H. Chen, Z. Li, X. Xiao, S. Yu, S. Yu, and X. Cai, “High-performance coherent optical modulators based on thin-film lithium niobate platform,” Nat. Commun. 11, 3911 (2020).
[Crossref]

Mercante, A.

A. N. R. Ahmed, S. Shi, A. Mercante, S. Nelan, P. Yao, and D. W. Prather, “High-efficiency lithium niobate modulator for K band operation,” APL Photon. 5, 091302 (2020).
[Crossref]

Mercante, A. J.

Minakata, M.

K. Aoki, J. Kondou, O. Mitomi, and M. Minakata, “Velocity-matching conditions for ultrahigh-speed optical LiNbO3 modulators with traveling-wave electrode,” Jpn. J. Appl. Phys. 45, 8696–8698 (2006).
[Crossref]

Mitomi, O.

K. Aoki, J. Kondou, O. Mitomi, and M. Minakata, “Velocity-matching conditions for ultrahigh-speed optical LiNbO3 modulators with traveling-wave electrode,” Jpn. J. Appl. Phys. 45, 8696–8698 (2006).
[Crossref]

Miura, H.

Miyamoto, Y.

Mourou, G. A.

M. Y. Frankel, S. Gupta, J. A. Valdmanis, and G. A. Mourou, “Terahertz attenuation and dispersion characteristics of coplanar transmission lines,” IEEE Trans. Microw. Theory Tech. 39, 910–916 (1991).
[Crossref]

Murphy, E.

E. Wooten, K. Kissa, A. Yi-Yan, E. Murphy, D. Lafaw, P. Hallemeier, D. Maack, D. Attanasio, D. Fritz, G. McBrien, and D. Bossi, “A review of lithium niobate modulators for fiber-optic communications systems,” IEEE J. Sel. Top. Quantum Electron. 6, 69–82 (2000).
[Crossref]

Nagarajan, R.

R. Nagarajan, “Technique for measuring the VPI-AC of a Mach-Zehnder modulator,” U.S. patent6,204,954 (September22, 1999).

Nagatani, M.

Nakamura, M.

Namiki, S.

Nelan, S.

A. N. R. Ahmed, S. Shi, A. Mercante, S. Nelan, P. Yao, and D. W. Prather, “High-efficiency lithium niobate modulator for K band operation,” APL Photon. 5, 091302 (2020).
[Crossref]

Nelson, R.

V. E. Stenger, J. Toney, A. Ponick, D. Brown, B. Griffin, R. Nelson, and S. Sriram, “Low loss and low VPI thin film lithium niobate on quartz electro-optic modulators,” in European Conference on Optical Communication (ECOC) (2017), pp. 1–3.

Norman, J.

Nunoya, N.

Ogiso, Y.

Ohtsuka, M.

Okano, M.

Ozaki, J.

Ozturk, C.

J. Shin, C. Ozturk, S. R. Sakamoto, Y. J. Chiu, and N. Dagli, “Novel T-rail electrodes for substrate removed low-voltage high-speed GaAs/AlGaAs electrooptic modulators,” IEEE Trans. Microw. Theory Tech. 53, 636–643 (2005).
[Crossref]

Pan, A.

Pan, Y.

M. Xu, M. He, H. Zhang, J. Jian, Y. Pan, X. Liu, L. Chen, X. Meng, H. Chen, Z. Li, X. Xiao, S. Yu, S. Yu, and X. Cai, “High-performance coherent optical modulators based on thin-film lithium niobate platform,” Nat. Commun. 11, 3911 (2020).
[Crossref]

Peter Orlando, W.

W. Peter Orlando, V. Forrest, Z. Jie, L. Huiyan, and M. Shayan, “Design of high-bandwidth, low-voltage and low-loss hybrid lithium niobate electro-optic modulators,” J. Phys. Photon. 3, 012001 (2020).
[Crossref]

Petropoulos, P.

Ponick, A.

V. E. Stenger, J. Toney, A. Ponick, D. Brown, B. Griffin, R. Nelson, and S. Sriram, “Low loss and low VPI thin film lithium niobate on quartz electro-optic modulators,” in European Conference on Optical Communication (ECOC) (2017), pp. 1–3.

Prather, D. W.

A. N. R. Ahmed, S. Shi, A. Mercante, S. Nelan, P. Yao, and D. W. Prather, “High-efficiency lithium niobate modulator for K band operation,” APL Photon. 5, 091302 (2020).
[Crossref]

A. J. Mercante, S. Shi, P. Yao, L. Xie, R. M. Weikle, and D. W. Prather, “Thin film lithium niobate electro-optic modulator with terahertz operating bandwidth,” Opt. Express 26, 14810–14816 (2018).
[Crossref]

Pupalaikis, P.

Qiu, F.

Rahman, B. M. A.

Randel, S.

Rao, A.

A. Rao and S. Fathpour, “Compact lithium niobate electrooptic modulators,” IEEE J. Sel. Top. Quantum Electron. 24, 3400114 (2018).
[Crossref]

A. Honardoost, R. Safian, A. Rao, and S. Fathpour, “High-speed modeling of ultracompact electrooptic modulators,” J. Lightwave Technol. 36, 5893–5902 (2018).
[Crossref]

Raybon, G.

Reed, G. T.

Safian, R.

Sakamoto, S. R.

J. Shin, S. R. Sakamoto, and N. Dagli, “Conductor loss of capacitively loaded slow wave electrodes for high-speed photonic devices,” J. Lightwave Technol. 29, 48–52 (2011).
[Crossref]

J. Shin, C. Ozturk, S. R. Sakamoto, Y. J. Chiu, and N. Dagli, “Novel T-rail electrodes for substrate removed low-voltage high-speed GaAs/AlGaAs electrooptic modulators,” IEEE Trans. Microw. Theory Tech. 53, 636–643 (2005).
[Crossref]

Seki, M.

Shakoor, A.

Shams-Ansari, A.

Shayan, M.

W. Peter Orlando, V. Forrest, Z. Jie, L. Huiyan, and M. Shayan, “Design of high-bandwidth, low-voltage and low-loss hybrid lithium niobate electro-optic modulators,” J. Phys. Photon. 3, 012001 (2020).
[Crossref]

Shi, S.

A. N. R. Ahmed, S. Shi, A. Mercante, S. Nelan, P. Yao, and D. W. Prather, “High-efficiency lithium niobate modulator for K band operation,” APL Photon. 5, 091302 (2020).
[Crossref]

A. J. Mercante, S. Shi, P. Yao, L. Xie, R. M. Weikle, and D. W. Prather, “Thin film lithium niobate electro-optic modulator with terahertz operating bandwidth,” Opt. Express 26, 14810–14816 (2018).
[Crossref]

Shin, J.

J. Shin, S. R. Sakamoto, and N. Dagli, “Conductor loss of capacitively loaded slow wave electrodes for high-speed photonic devices,” J. Lightwave Technol. 29, 48–52 (2011).
[Crossref]

J. Shin, C. Ozturk, S. R. Sakamoto, Y. J. Chiu, and N. Dagli, “Novel T-rail electrodes for substrate removed low-voltage high-speed GaAs/AlGaAs electrooptic modulators,” IEEE Trans. Microw. Theory Tech. 53, 636–643 (2005).
[Crossref]

Sriram, S.

V. E. Stenger, J. Toney, A. Ponick, D. Brown, B. Griffin, R. Nelson, and S. Sriram, “Low loss and low VPI thin film lithium niobate on quartz electro-optic modulators,” in European Conference on Optical Communication (ECOC) (2017), pp. 1–3.

Stenger, V. E.

V. E. Stenger, J. Toney, A. Ponick, D. Brown, B. Griffin, R. Nelson, and S. Sriram, “Low loss and low VPI thin film lithium niobate on quartz electro-optic modulators,” in European Conference on Optical Communication (ECOC) (2017), pp. 1–3.

Sugiyama, M.

M. Doi, M. Sugiyama, K. Tanaka, and M. Kawai, “Advanced LiNbO3 optical modulators for broadband optical communications,” IEEE J. Sel. Top. Quantum Electron. 12, 745–750 (2006).
[Crossref]

Sun, C.

X. Liu, B. Xiong, C. Sun, Z. Hao, L. Wang, J. Wang, Y. Han, H. Li, J. Yu, and Y. Luo, “Low half-wave-voltage thin film LiNbO3 electro-optic modulator based on a compact electrode structure,” in Asia Communications and Photonics Conference/International Conference on Information Photonics and Optical Communications (ACP/IPOC) (Optical Society of America, 2020), paper M4A.144.

Suzuki, K.

Takahashi, Y.

Tanaka, K.

M. Doi, M. Sugiyama, K. Tanaka, and M. Kawai, “Advanced LiNbO3 optical modulators for broadband optical communications,” IEEE J. Sel. Top. Quantum Electron. 12, 745–750 (2006).
[Crossref]

Tanizawa, K.

Tanobe, H.

Teng, M.

Thomson, D. J.

Toney, J.

V. E. Stenger, J. Toney, A. Ponick, D. Brown, B. Griffin, R. Nelson, and S. Sriram, “Low loss and low VPI thin film lithium niobate on quartz electro-optic modulators,” in European Conference on Optical Communication (ECOC) (2017), pp. 1–3.

Tran, D.

Ueda, Y.

Urick, V. J.

V. J. Urick, J. D. McKinney, and K. J. Williams, Fundamentals of Microwave Photonics, Wiley Series in Microwave and Optical Engineering (Wiley, 2015).

Valdmanis, J. A.

M. Y. Frankel, S. Gupta, J. A. Valdmanis, and G. A. Mourou, “Terahertz attenuation and dispersion characteristics of coplanar transmission lines,” IEEE Trans. Microw. Theory Tech. 39, 910–916 (1991).
[Crossref]

Wakita, H.

Wang, C.

Wang, J.

X. Liu, B. Xiong, C. Sun, Z. Hao, L. Wang, J. Wang, Y. Han, H. Li, J. Yu, and Y. Luo, “Low half-wave-voltage thin film LiNbO3 electro-optic modulator based on a compact electrode structure,” in Asia Communications and Photonics Conference/International Conference on Information Photonics and Optical Communications (ACP/IPOC) (Optical Society of America, 2020), paper M4A.144.

J. Zhou, J. Wang, L. Zhu, Q. Zhang, Q. Zhang, and J. Hong, “Silicon photonics carrier depletion modulators capable of 85Gbaud 16QAM and 64Gbaud 64QAM,” in Optical Fiber Communication Conference (Optical Society of America, 2019), paper Tu2H.2.

Wang, L.

M. Li, L. Wang, X. Li, X. Xiao, and S. Yu, “Silicon intensity Mach-Zehnder modulator for single lane 100 Gb/s applications,” Photon. Res. 6, 109–116 (2018).
[Crossref]

X. Liu, B. Xiong, C. Sun, Z. Hao, L. Wang, J. Wang, Y. Han, H. Li, J. Yu, and Y. Luo, “Low half-wave-voltage thin film LiNbO3 electro-optic modulator based on a compact electrode structure,” in Asia Communications and Photonics Conference/International Conference on Information Photonics and Optical Communications (ACP/IPOC) (Optical Society of America, 2020), paper M4A.144.

Watanabe, T.

M. Burla, C. Hoessbacher, W. Heni, C. Haffner, Y. Fedoryshyn, D. Werner, T. Watanabe, H. Massler, D. L. Elder, L. R. Dalton, and J. Leuthold, “500 GHz plasmonic Mach-Zehnder modulator enabling sub-THz microwave photonics,” APL Photon. 4, 056106 (2019).
[Crossref]

Weikle, R. M.

Werner, D.

M. Burla, C. Hoessbacher, W. Heni, C. Haffner, Y. Fedoryshyn, D. Werner, T. Watanabe, H. Massler, D. L. Elder, L. R. Dalton, and J. Leuthold, “500 GHz plasmonic Mach-Zehnder modulator enabling sub-THz microwave photonics,” APL Photon. 4, 056106 (2019).
[Crossref]

Williams, K. J.

V. J. Urick, J. D. McKinney, and K. J. Williams, Fundamentals of Microwave Photonics, Wiley Series in Microwave and Optical Engineering (Wiley, 2015).

Winzer, P.

C. Wang, M. Zhang, X. Chen, M. Bertrand, A. Shams-Ansari, S. Chandrasekhar, P. Winzer, and M. Loncar, “Integrated lithium niobate electro-optic modulators operating at CMOS-compatible voltages,” Nature 562, 101–104 (2018).
[Crossref]

Winzer, P. J.

Wolf, S.

Wooten, E.

E. Wooten, K. Kissa, A. Yi-Yan, E. Murphy, D. Lafaw, P. Hallemeier, D. Maack, D. Attanasio, D. Fritz, G. McBrien, and D. Bossi, “A review of lithium niobate modulators for fiber-optic communications systems,” IEEE J. Sel. Top. Quantum Electron. 6, 69–82 (2000).
[Crossref]

Xia, J.

Xiao, X.

M. Xu, M. He, H. Zhang, J. Jian, Y. Pan, X. Liu, L. Chen, X. Meng, H. Chen, Z. Li, X. Xiao, S. Yu, S. Yu, and X. Cai, “High-performance coherent optical modulators based on thin-film lithium niobate platform,” Nat. Commun. 11, 3911 (2020).
[Crossref]

M. Li, L. Wang, X. Li, X. Xiao, and S. Yu, “Silicon intensity Mach-Zehnder modulator for single lane 100 Gb/s applications,” Photon. Res. 6, 109–116 (2018).
[Crossref]

Xie, L.

Xiong, B.

X. Liu, B. Xiong, C. Sun, Z. Hao, L. Wang, J. Wang, Y. Han, H. Li, J. Yu, and Y. Luo, “Low half-wave-voltage thin film LiNbO3 electro-optic modulator based on a compact electrode structure,” in Asia Communications and Photonics Conference/International Conference on Information Photonics and Optical Communications (ACP/IPOC) (Optical Society of America, 2020), paper M4A.144.

Xu, J.

Xu, M.

M. Xu, M. He, H. Zhang, J. Jian, Y. Pan, X. Liu, L. Chen, X. Meng, H. Chen, Z. Li, X. Xiao, S. Yu, S. Yu, and X. Cai, “High-performance coherent optical modulators based on thin-film lithium niobate platform,” Nat. Commun. 11, 3911 (2020).
[Crossref]

Yamada, K.

Yamazaki, H.

Yan, X.

Yang, Y.

Yao, P.

A. N. R. Ahmed, S. Shi, A. Mercante, S. Nelan, P. Yao, and D. W. Prather, “High-efficiency lithium niobate modulator for K band operation,” APL Photon. 5, 091302 (2020).
[Crossref]

A. J. Mercante, S. Shi, P. Yao, L. Xie, R. M. Weikle, and D. W. Prather, “Thin film lithium niobate electro-optic modulator with terahertz operating bandwidth,” Opt. Express 26, 14810–14816 (2018).
[Crossref]

Yasuda, T.

Yi-Yan, A.

E. Wooten, K. Kissa, A. Yi-Yan, E. Murphy, D. Lafaw, P. Hallemeier, D. Maack, D. Attanasio, D. Fritz, G. McBrien, and D. Bossi, “A review of lithium niobate modulators for fiber-optic communications systems,” IEEE J. Sel. Top. Quantum Electron. 6, 69–82 (2000).
[Crossref]

Yokoyama, N.

Yokoyama, S.

Yu, J.

X. Liu, B. Xiong, C. Sun, Z. Hao, L. Wang, J. Wang, Y. Han, H. Li, J. Yu, and Y. Luo, “Low half-wave-voltage thin film LiNbO3 electro-optic modulator based on a compact electrode structure,” in Asia Communications and Photonics Conference/International Conference on Information Photonics and Optical Communications (ACP/IPOC) (Optical Society of America, 2020), paper M4A.144.

Yu, P. K. L.

Yu, S.

M. Xu, M. He, H. Zhang, J. Jian, Y. Pan, X. Liu, L. Chen, X. Meng, H. Chen, Z. Li, X. Xiao, S. Yu, S. Yu, and X. Cai, “High-performance coherent optical modulators based on thin-film lithium niobate platform,” Nat. Commun. 11, 3911 (2020).
[Crossref]

M. Xu, M. He, H. Zhang, J. Jian, Y. Pan, X. Liu, L. Chen, X. Meng, H. Chen, Z. Li, X. Xiao, S. Yu, S. Yu, and X. Cai, “High-performance coherent optical modulators based on thin-film lithium niobate platform,” Nat. Commun. 11, 3911 (2020).
[Crossref]

M. Li, L. Wang, X. Li, X. Xiao, and S. Yu, “Silicon intensity Mach-Zehnder modulator for single lane 100 Gb/s applications,” Photon. Res. 6, 109–116 (2018).
[Crossref]

Zeng, C.

Zhang, G.

Zhang, H.

M. Xu, M. He, H. Zhang, J. Jian, Y. Pan, X. Liu, L. Chen, X. Meng, H. Chen, Z. Li, X. Xiao, S. Yu, S. Yu, and X. Cai, “High-performance coherent optical modulators based on thin-film lithium niobate platform,” Nat. Commun. 11, 3911 (2020).
[Crossref]

Zhang, M.

Zhang, Q.

J. Zhou, J. Wang, L. Zhu, Q. Zhang, Q. Zhang, and J. Hong, “Silicon photonics carrier depletion modulators capable of 85Gbaud 16QAM and 64Gbaud 64QAM,” in Optical Fiber Communication Conference (Optical Society of America, 2019), paper Tu2H.2.

J. Zhou, J. Wang, L. Zhu, Q. Zhang, Q. Zhang, and J. Hong, “Silicon photonics carrier depletion modulators capable of 85Gbaud 16QAM and 64Gbaud 64QAM,” in Optical Fiber Communication Conference (Optical Society of America, 2019), paper Tu2H.2.

Zhang, R.

Zhang, W.

Zhou, J.

J. Zhou, J. Wang, L. Zhu, Q. Zhang, Q. Zhang, and J. Hong, “Silicon photonics carrier depletion modulators capable of 85Gbaud 16QAM and 64Gbaud 64QAM,” in Optical Fiber Communication Conference (Optical Society of America, 2019), paper Tu2H.2.

Zhu, L.

J. Zhou, J. Wang, L. Zhu, Q. Zhang, Q. Zhang, and J. Hong, “Silicon photonics carrier depletion modulators capable of 85Gbaud 16QAM and 64Gbaud 64QAM,” in Optical Fiber Communication Conference (Optical Society of America, 2019), paper Tu2H.2.

Zhu, R.

Zhuang, L.

Zwickel, H.

APL Photon. (2)

M. Burla, C. Hoessbacher, W. Heni, C. Haffner, Y. Fedoryshyn, D. Werner, T. Watanabe, H. Massler, D. L. Elder, L. R. Dalton, and J. Leuthold, “500 GHz plasmonic Mach-Zehnder modulator enabling sub-THz microwave photonics,” APL Photon. 4, 056106 (2019).
[Crossref]

A. N. R. Ahmed, S. Shi, A. Mercante, S. Nelan, P. Yao, and D. W. Prather, “High-efficiency lithium niobate modulator for K band operation,” APL Photon. 5, 091302 (2020).
[Crossref]

Appl. Opt. (1)

Appl. Phys. Lett. (1)

M. Lee, “Dielectric constant and loss tangent in LiNbO3 crystals from 90 to 147 GHz,” Appl. Phys. Lett. 79, 1342–1344 (2001).
[Crossref]

IEEE J. Sel. Top. Quantum Electron. (3)

A. Rao and S. Fathpour, “Compact lithium niobate electrooptic modulators,” IEEE J. Sel. Top. Quantum Electron. 24, 3400114 (2018).
[Crossref]

M. Doi, M. Sugiyama, K. Tanaka, and M. Kawai, “Advanced LiNbO3 optical modulators for broadband optical communications,” IEEE J. Sel. Top. Quantum Electron. 12, 745–750 (2006).
[Crossref]

E. Wooten, K. Kissa, A. Yi-Yan, E. Murphy, D. Lafaw, P. Hallemeier, D. Maack, D. Attanasio, D. Fritz, G. McBrien, and D. Bossi, “A review of lithium niobate modulators for fiber-optic communications systems,” IEEE J. Sel. Top. Quantum Electron. 6, 69–82 (2000).
[Crossref]

IEEE Trans. Instrum. Meas. (1)

R. G. Geyer and J. Krupka, “Microwave dielectric properties of anisotropic materials at cryogenic temperatures,” IEEE Trans. Instrum. Meas. 44, 329–331 (1995).
[Crossref]

IEEE Trans. Microw. Theory Tech. (2)

J. Shin, C. Ozturk, S. R. Sakamoto, Y. J. Chiu, and N. Dagli, “Novel T-rail electrodes for substrate removed low-voltage high-speed GaAs/AlGaAs electrooptic modulators,” IEEE Trans. Microw. Theory Tech. 53, 636–643 (2005).
[Crossref]

M. Y. Frankel, S. Gupta, J. A. Valdmanis, and G. A. Mourou, “Terahertz attenuation and dispersion characteristics of coplanar transmission lines,” IEEE Trans. Microw. Theory Tech. 39, 910–916 (1991).
[Crossref]

IRE Trans. Microw. Theory Tech. (1)

A. F. Harvey, “Periodic and guiding structures at microwave frequencies,” IRE Trans. Microw. Theory Tech. 8, 30–61 (1960).
[Crossref]

J. Lightwave Technol. (8)

K. Ashida, M. Okano, T. Yasuda, M. Ohtsuka, M. Seki, N. Yokoyama, K. Koshino, K. Yamada, and Y. Takahashi, “Photonic crystal nanocavities with an average Q factor of 1.9 million fabricated on a 300-mm-wide SOI wafer using a CMOS-compatible process,” J. Lightwave Technol. 36, 4774–4782 (2018).
[Crossref]

J. Shin, S. R. Sakamoto, and N. Dagli, “Conductor loss of capacitively loaded slow wave electrodes for high-speed photonic devices,” J. Lightwave Technol. 29, 48–52 (2011).
[Crossref]

R. Ding, Y. Liu, Y. Ma, Y. Yang, Q. Li, A. E. Lim, G. Lo, K. Bergman, T. Baehr-Jones, and M. Hochberg, “High-speed silicon modulator with slow-wave electrodes and fully independent differential drive,” J. Lightwave Technol. 32, 2240–2247 (2014).
[Crossref]

X. Chen, S. Chandrasekhar, S. Randel, G. Raybon, A. Adamiecki, P. Pupalaikis, and P. J. Winzer, “All-electronic 100-GHz bandwidth digital-to-analog converter generating PAM signals up to 190 GBaud,” J. Lightwave Technol. 35, 411–417 (2017).
[Crossref]

G. L. Li, T. G. B. Mason, and P. K. L. Yu, “Analysis of segmented traveling-wave optical modulators,” J. Lightwave Technol. 22, 1789–1796 (2004).
[Crossref]

Y. Ogiso, J. Ozaki, Y. Ueda, H. Wakita, M. Nagatani, H. Yamazaki, M. Nakamura, T. Kobayashi, S. Kanazawa, Y. Hashizume, H. Tanobe, N. Nunoya, M. Ida, Y. Miyamoto, and M. Ishikawa, “80-GHz bandwidth and 1.5-v VPI InP-based IQ modulator,” J. Lightwave Technol. 38, 249–255 (2020).
[Crossref]

P. Bhasker, J. Norman, J. Bowers, and N. Dagli, “Low voltage, high optical power handling capable, bulk compound semiconductor electro-optic modulators at 1550 nm,” J. Lightwave Technol. 38, 2308–2314 (2020).
[Crossref]

A. Honardoost, R. Safian, A. Rao, and S. Fathpour, “High-speed modeling of ultracompact electrooptic modulators,” J. Lightwave Technol. 36, 5893–5902 (2018).
[Crossref]

J. Phys. Photon. (1)

W. Peter Orlando, V. Forrest, Z. Jie, L. Huiyan, and M. Shayan, “Design of high-bandwidth, low-voltage and low-loss hybrid lithium niobate electro-optic modulators,” J. Phys. Photon. 3, 012001 (2020).
[Crossref]

Jpn. J. Appl. Phys. (1)

K. Aoki, J. Kondou, O. Mitomi, and M. Minakata, “Velocity-matching conditions for ultrahigh-speed optical LiNbO3 modulators with traveling-wave electrode,” Jpn. J. Appl. Phys. 45, 8696–8698 (2006).
[Crossref]

Nat. Commun. (1)

M. Xu, M. He, H. Zhang, J. Jian, Y. Pan, X. Liu, L. Chen, X. Meng, H. Chen, Z. Li, X. Xiao, S. Yu, S. Yu, and X. Cai, “High-performance coherent optical modulators based on thin-film lithium niobate platform,” Nat. Commun. 11, 3911 (2020).
[Crossref]

Nature (1)

C. Wang, M. Zhang, X. Chen, M. Bertrand, A. Shams-Ansari, S. Chandrasekhar, P. Winzer, and M. Loncar, “Integrated lithium niobate electro-optic modulators operating at CMOS-compatible voltages,” Nature 562, 101–104 (2018).
[Crossref]

Opt. Express (6)

Opt. Lett. (3)

Optica (3)

Photon. Res. (1)

Other (9)

J. Zhou, J. Wang, L. Zhu, Q. Zhang, Q. Zhang, and J. Hong, “Silicon photonics carrier depletion modulators capable of 85Gbaud 16QAM and 64Gbaud 64QAM,” in Optical Fiber Communication Conference (Optical Society of America, 2019), paper Tu2H.2.

V. J. Urick, J. D. McKinney, and K. J. Williams, Fundamentals of Microwave Photonics, Wiley Series in Microwave and Optical Engineering (Wiley, 2015).

R. W. Boyd, Nonlinear Optics (Elsevier, 2008).

V. E. Stenger, J. Toney, A. Ponick, D. Brown, B. Griffin, R. Nelson, and S. Sriram, “Low loss and low VPI thin film lithium niobate on quartz electro-optic modulators,” in European Conference on Optical Communication (ECOC) (2017), pp. 1–3.

G. Betts, “Velocity matching electrode structure for electro-optic modulators,” U.S. patent6,310,700 (October30, 2001).

X. Liu, B. Xiong, C. Sun, Z. Hao, L. Wang, J. Wang, Y. Han, H. Li, J. Yu, and Y. Luo, “Low half-wave-voltage thin film LiNbO3 electro-optic modulator based on a compact electrode structure,” in Asia Communications and Photonics Conference/International Conference on Information Photonics and Optical Communications (ACP/IPOC) (Optical Society of America, 2020), paper M4A.144.

R. Nagarajan, “Technique for measuring the VPI-AC of a Mach-Zehnder modulator,” U.S. patent6,204,954 (September22, 1999).

Thorlabs, Lithium Niobate Electro-Optic Modulators, Fiber-Coupled (2020).

Fujitsu, Low Drive Voltage 40 Gb/s NRZ LiNBO3 External Modulator (2020).

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Figures (4)

Fig. 1.
Fig. 1. Low-voltage high-bandwidth traveling-wave integrated lithium niobate (LN) modulator with segmented electrodes. (a) Artistic top view of the modulator design (not to scale) where RF signal co-propagates with the optical signal. (b) Scanning electron microscope image of the fabricated device. Scale bar: 50 µm. (c) Artistic angled view of a regular electrode design. Current (red) crowds at edges of the conductors. (d) Artistic angled view of a segmented design. Current crowds less and distributes more uniformly. (e) Cross sectional view of the phase shifter. Design parameters $(g,h,s,t,r,c,{w_s}) = (5,6,2,6,45,5,100)\;{{\unicode{x00B5}{\rm m}}}$.
Fig. 2.
Fig. 2. Measured RF losses and phase indices of a 10 mm long regular electrode on LN-on-silicon and a segmented electrode on LN-on-quartz. (a) Measured RF losses on linear frequency axis. (b) Measured RF losses on square-root frequency axis. (c) Measured RF phase indices.
Fig. 3.
Fig. 3. Electro-optic performance of segmented LN modulators. (a) Measured DC ${V_\pi}$ and extinction for a 20 mm long modulator. (b) Measured EO responses and electrical reflections (${S_{11}}$) referenced to RF ${V_\pi}$ at 1 GHz for a 10 mm and a 20 mm long modulator. The responses are normalized to photodiode electric signal, i.e., ${V_{\pi ,{{3}} {\text -} {\rm{dB}}}} \sim 1.4{V_{\pi ,1\;{\rm{GHz}}}}$ and ${V_{\pi ,{{6}} {\text -} {\rm{dB}}}} \sim 2{V_{\pi ,1\;{\rm{GHz}}}}$. The length independent ripples in the EO response curves are caused by uncertainty in photodetector response (Newport 1014), which is numerically de-embedded from manufacture’s data sheet.
Fig. 4.
Fig. 4. Comparison of micro-structured modulator performance to prior designs and predictions on high frequency performances. (a) Measured voltage–bandwidth (1 dB) performance comparison of legacy LN ($0.3\;{\rm{dB}}\;{\rm{c}}{{\rm{m}}^{- 1}}\;{\rm{GH}}{{\rm{z}}^{- 1/2}}$, $15\;{\rm{V}} \cdot {\rm{cm}}$), thin-film regular LN ($0.69\;{\rm{c}}{{\rm{m}}^{- 1}}\;{\rm{GH}}{{\rm{z}}^{- 1/2}}$, $2.1\;{\rm{V}} \cdot {\rm{cm}}$), and thin-film segmented LN modulators ($0.26\;{\rm{c}}{{\rm{m}}^{- 1}}\;{\rm{GH}}{{\rm{z}}^{- 1/2}}$, $2.3\;{\rm{V}} \cdot {\rm{cm}}$). The shaded areas correspond to improved design space with other substrates. (b) Predicted performances of 20 mm long electrode for regular and segmented design up to 200 GHz bandwidth. Material legends indicate the substrate handle. (c) Velocity matching tolerances of segmented modulator with two different lengths. Curves represent EO bandwidth.

Tables (1)

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Table 1. Comparison of Simulated Performance for Various Electrode Designs

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