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Accepted papers to appear in an upcoming issue

Optica Publishing Group posts prepublication articles as soon as they are accepted and cleared for production. See the FAQ for additional information.

Integrated optical gyroscope employing high performance silicon nitride resonator

Changkun Feng, Yonggui Zhang, Honghao Ma, Hui Li, and Li Shuang Feng

DOI: 10.1364/PRJ.456321 Received 14 Feb 2022; Accepted 22 May 2022; Posted 23 May 2022  View: PDF

Abstract: High performance waveguide resonator is the key component to the application of resonant integrated optical gyroscope (RIOG). And the silicon nitride (Si3N4) waveguide with ultra-aspect-ratio is expected to realize the single-polarization of the resonator suppress polarization noise of the RIOG. In this paper, we successfully fabricated a Si3N4 resonator with bending radius of 17.5 mm, which the finesse (F) is 150, the quality factor (Q) is 1.54×107, and the propagation loss is 1.2 dB/m, respectively. Employing the Si3N4 resonator, a double closed-loop RIOG is set up and the performance of the RIOG system is experimentally studied. A long-term bias stability (3600s) of 13.2 °/h is successfully demonstrated at room temperature. More importantly, at 40 ℃, 50 ℃ and 60 ℃, the long-term bias stability of RIOG is 14.8 °/h ,21.2 °/h and .6 °/h, respectively, which show wonderful temperature performance. To the best of our knowledge, this is the best reported to date for the Si3N4 resonator based RIOG. This advancement paves the way for the application of RIOG.

The synergistic enhancement of spin-phonon interaction in a hybrid system

Yuan Zhou, Chang-Sheng Hu, Xinke Li, Dong Lv, Hai Huang, Yong Xiong, and Xin Lu

DOI: 10.1364/PRJ.459794 Received 07 Apr 2022; Accepted 21 May 2022; Posted 23 May 2022  View: PDF

Abstract: The investigation on significantly enhancing the coupling to NV centers at single-quanta level is of great key point to further explore its application in quantum information processing (QIP). We here study a joint scheme to further enhance NV-phonon coherent coupling with two methods working together in a hybrid optomechanical systems. Both methods are mechanic-induced mode field coupling (MFC) leading to the modification of the spatial distribution of the opticalfield, and the mechanical parametric amplification (MPA) realized by modulating the mechanical spring constant in time, respectively. With the joint assistance of MFC and MPA, the coherent coupling between the NV spin and one supermode of the mechanical resonators (MRs) can be further enhanced significantly, with the rate ∝ ne^r, several potential applications on this proposal are also discussed in this work. For the ultimate target of enhancing the coupling to NV spin at single-quanta level, this attempt may provide a promising spin-phonon platform forimplementing the more active control.

A Proof-of-Principle Demonstration of Quantum microwave photonics

Yaqing Jin, Hong Huibo, Ye Yang, Xiao Xiang, Quan Run ai, Tao Liu, Shou-Gang Zhang, Ming Li, Ninghua Zhu, and Ruifang Dong

DOI: 10.1364/PRJ.453934 Received 14 Jan 2022; Accepted 19 May 2022; Posted 19 May 2022  View: PDF

Abstract: With the rapid development of microwave photonics, which has expanded to numerous applications of commercial importance, eliminating the emerging bottlenecks has become vital. For example, as the main branch of microwave photonics, radio-over-fiber technology provides high bandwidth, low-loss, and long-distance propagation capability, facilitating wide applications ranging from telecommunication to wireless networks. With ultrashort pulses as the optical carrier, huge capacity is further endowed. However, the wide bandwidth of ultrashort pulses results in the severe vulnerability of high-frequency RF signals to fiber dispersion. A quantum microwave photonics method is proposed and demonstrated experimentally with a time-energy entangled biphoton source as the optical carrier and combined with the single-photon detection technique. The results show that it not only realizes unprecedented nonlocal RF signal modulation with strong resistance to the dispersion associated with ultrashort pulse carriers but provides an alternative mechanism to distill the RF signal out from the dispersion effectively. Furthermore, the spurious-free dynamic ranges of the nonlocally modulated and distilled RF signals have been significantly improved. With the ultra-weak detection and high-speed processing advantages endowed by the low-timing-jitter single-photon detection, the quantum microwave photonics method opens up new possibilities in modern communication and networks.

Colloidal Quantum-dot Light Emitting Diodes with Bias-tunable Color

Ge Mu, Tianyu Rao, Menglu Chen, Yimei Tan, Qun Hao, and Xin Tang

DOI: 10.1364/PRJ.456043 Received 11 Feb 2022; Accepted 18 May 2022; Posted 19 May 2022  View: PDF

Abstract: Although the performance of quantum dots-based light emitting diodes (QLEDs) has been significantly enhanced over the past years, conventional full-color QLEDs displays still rely on the side-by-side pattern techniques of red (R)/green (G)/blue (B) QDs. Such lateral integration of multi-color pixels imposes technological difficulty in the development of high-resolution displays due to limited pixel density and filling factors. Herein, we demonstrate the unprecedent development of full-color QLEDs with bias-tunable emission spectrum by engineering mixed R/G/B QDs as light-emitting layers. In Commission International de I’Eclairage (CIE) chromaticity coordinates, the QLEDs with bias-tunable color exhibit wide color variation ranging from the red (0.649, 0.330), green (0.283, 0.305) to blue (0.255,0.264) upon increasing voltages and can be tuned to emit white light (0.316,0.325). More importantly, the fabricated multi-color QLEDs show low turn-on voltage down to 2 V, high luminance approaching 103 cd m-2, and superior external quantum efficiency (EQE) of 13.3%, which is competitive with state-of-art single-color QLEDs. Benefitting the wide spectral tunability and light emitting efficiency, we believe the proposed multi-color QLEDs have great application prospect for both displays and lighting.

Sn content gradient GeSn with strain controlled for high performance GeSn mid-infrared photodetectors

Xiangquan Liu, Jun Zheng, Chaoqun Niu, Taoran Liu, Qinxing Huang, Mingming Li, Diandian Zhang, Yaqing Pan, zhi Liu, Yuhua Zuo, and Buwen Cheng

DOI: 10.1364/PRJ.456000 Received 10 Feb 2022; Accepted 17 May 2022; Posted 17 May 2022  View: PDF

Abstract: GeSn mid-infrared detector have attracted a lot of attention for Si infrared photonics, due to its compatibility with Si complementary metal oxide semiconductor technology. The GeSn bandgap is affected by the Sn composition and strain, which determining the working wavelength range of detector. By applying the Sn content gradient GeSn layer structure method, the strain of GeSn can be controlled from the full strain to complete relaxation. The strain evolution of GeSn alloys were investigated in detail and the effectiveness of gradually increasing Sn composition for the growth of high-quality and high-Sn-content GeSn alloys was revealed. The relax GeSn thick film with the Sn composition up to 16.3% was grown and the GeSn photodetectors were fabricated. The photodectectors shown cutoff wavelength up to 4.7 μm and the peak responsivity was 0.35 A/W under 1 V at 2.53 μm at 77 K. These results indicate that GeSn alloy grown with Sn content gradient structure has promising application in mid-infrared detection.

Stimulated generation of deterministic platicon frequency microcombs

Hao Liu, Shu-Wei Huang, Jinghui Yang, Wenting Wang, Mingbin Yu, Dim-Lee Kwong, Pierre Colman, and Chee Wei Wong

DOI: 10.1364/PRJ.459403 Received 28 Mar 2022; Accepted 15 May 2022; Posted 16 May 2022  View: PDF

Abstract: Dissipative Kerr soliton generation in chip-scale nonlinear resonators has recently observed remarkable advances, spanning from massively-parallel communications, self-referenced oscillators, to dual-comb spectroscopy. Often working in the anomalous dispersion regime, unique driving protocols and dispersion in these nonlinear resonators have been examined to achieve the soliton and soliton-like temporal pulse shapes and coherent frequency comb generation. The normal dispersion regime provides a complementary approach to bridge the nonlinear dynamical studies, including the possibility of square pulse formation with flat-top plateaus, or platicons. Here we report observations of square pulse formation in chip-scale frequency combs, through stimulated pumping at one free-spectral-range and in silicon nitride rings with +55 fs2/mm normal group velocity dispersion. Tuning of the platicon frequency comb via a varied sideband modulation frequency is examined in both spectral and temporal measurements. Determined by second-harmonic auto-correlation and cross-correlation, we observe bright square platicon pulse of 17 ps pulsewidth on a 19 GHz flat frequency comb. With auxiliary-laser-assisted thermal stabilization, we surpass the thermal bistable dragging and extend the mode-locking access to narrower 2 ps platicon pulse states, supported by nonlinear dynamical modeling and boundary limit discussions.

Synthetic aperture ptychography (SAP): coded sensor translation for joint spatial-Fourier bandwidth expansion

Guoan Zheng, Pengming Song, Shaowei Jiang, Tianbo Wang, Chengfei Guo, Ruihai Wang, and Terrance zhang

DOI: 10.1364/PRJ.460549 Received 07 Apr 2022; Accepted 15 May 2022; Posted 16 May 2022  View: PDF

Abstract: Conventional ptychography translates the object through a localized probe beam to widen the field of view in the real space. Fourier ptychography translates the object spectrum through a pupil aperture to expand the Fourier bandwidth in the reciprocal space. Here we report an imaging modality, termed Synthetic Aperture Ptychography (SAP), for getting the best of both worlds. In SAP, we illuminate the stationary object using an extended plane wave and translate a coded image sensor at the far-field for data acquisition. The coded layer attached on the sensor modulates the object exit waves and serves as an effective ptychographic probe for phase retrieval. The sensor translation process in SAP synthesizes a large complex-valued wavefront at the intermediate aperture plane. By propagating this wavefront back to the object plane, we can widen the field of view in the real space and expand the Fourier bandwidth in the reciprocal space simultaneously. We validate the SAP approach with transmission targets and reflection silicon microchips. A 20-mm aperture was synthesized using a 5-mm sensor, achieving a 4-fold gain in resolution and 16-fold gain in field of view for object recovery. In addition, the thin sample requirement in ptychography is no longer required in SAP. One can digitally propagate the recovered exit wave to any axial position for post-acquisition refocusing. The SAP scheme offers a solution for far-field super-resolution imaging without using lens. It can be adopted in coherent diffraction imaging setups with radiation sources from visible light, extreme ultraviolet, X-ray, to electron.

Experimental demonstration of robust nanophotonic devices optimized by topological inverse design with energy constraint

Guowu Zhang, Dan-Xia Xu, Yuri Grinberg, and Odile Liboiron-Ladouceur

DOI: 10.1364/PRJ.457066 Received 25 Feb 2022; Accepted 13 May 2022; Posted 16 May 2022  View: PDF

Abstract: In this paper, we present the experimental results for integrated photonic devices optimized with an energy-constrained inverse design method. When this constraint is applied, optimizations are directed to solutions that contain the optical field inside the waveguide core medium, leading to more robust designs with relatively larger minimum feature size. We optimize three components: a mode converter (MC), a 1310 nm/1550 nm wavelength duplexer and a three-channel C-band wavelength demultiplexer for coarse wavelength division multiplexing (CWDM) application with 50 nm channel spacing. The energy constraint leads to nearly binarized structures without applying independent binarization stage. It also reduces the appearance of small features. In the MC, well binarized design, improved insertion loss and crosstalk are obtained as a result. Furthermore, the proposed constraint improves the robustness to fabrication imperfections as shown in the duplexer design. With energy constraint optimization, the corresponding spectrum shifts for the duplexer under ±10 nm dimensional variations are reduced from 105 nm to 55 nm and from 72 nm to 60 nm for the 1310 nm and 1550 nm channel, respectively. In the CWDM demultiplexer, robustness towards ±10 nm fabrication error is improved by a factor of two. The introduction of the energy constraint into topological optimization demonstrates computational gain with better-performing designs.

Creation of cylindrical vector beams through highlyanisotropic scattering media with a single scalartransmission matrix calibration

Qian Zhao, Shijie Tu, Qiannan Lei, Cheng-Shan Guo, Qiwen Zhan, and Yangjian Cai

DOI: 10.1364/PRJ.457928 Received 14 Mar 2022; Accepted 11 May 2022; Posted 16 May 2022  View: PDF

Abstract: Cylindrical vector (CV) beams have attracted increasing interests due to their particular properties and their applications in optical imaging, manipulation and light matter interactions. However, it is challenging to construct CV beams through highly anisotropic scattering media(HASM) such as the thick biological tissue, posing a barrier to the applications of CV beams that involve HASM. Here, we present a scheme to construct CV beams beyond high scattering that only requires a single scalar transmission matrix (TM) measurement and manipulation of the spatial degrees of freedom at the input field. Assisted by a radial polarization converter (S-waveplate) and a polarizer, the scheme enables one to obtain the correct incident wavefront for the creation of CV beams through HASM with only one single scalar TM measurement. Compared to the existing method, this user-friendly approach is fast and simple in terms of the optical implements and computations. Both radially and azimuthally polarized beams are experimentally constructed through a ZnO scattering layer to demonstrate the viability of the method. Arbitrarily generalized CV beams and arrays of CV beams are also created through the HASM to further prove the flexibility of the method. We believe this work may pave the way for applications of CV beams that involve highly anisotropic scattering environment.

Lamb-dip Saturated-absorption CAvity Ring-down (SCAR) ro-vibrational molecular spectroscopy in the near-IR

Pasquale Maddaloni, roberto aiello, Valentina Di Sarno, maria giulia delli santi, Maurizio De Rosa, Iolanda Ricciardi, Giovanni Giusfredi, Paolo Natale, and Luigi Santamaria Amato

DOI: 10.1364/PRJ.456515 Received 22 Feb 2022; Accepted 10 May 2022; Posted 16 May 2022  View: PDF

Abstract: The high-detection-sensitivity saturated-absorption cavity ring-down (SCAR) technique is extended to Lamb-dip spectroscopy of ro-vibrational molecular transitions in the near-IR region. Frequency-comb-referenced sub-Doppler saturation measurements, performed on the acetylene (ν₁+ν₃+ν₄ <- ν₄) R(14)e line at 6562 cm-1, are analyzed by a SCAR global line profile (GLP) fitting routine, based on a specially developed theoretical model. Compared to a conventional cavity-ring-down evaluation, our approach yields dip profiles with a linewidth freed from saturation broadening effects, reduced by 40%, and a signal-to-noise ratio increased by 90%. Ultimately, an overall (statistical + systematic) fractional uncertainty as low as 7·10E-12 is achieved for the absolute line-center frequency. At the same time, our method is also able to accurately infer the linear (non-saturated) behaviour of the gas absorption, providing Lamb-dip-based linestrength measurements with a relative uncertainty of 5‰.

One-dimensional quasi bound states in the continuum in the ω~k space for nonlinear optical applications

Kaili Sun, Hui Jiang, Dmitry Bykov, Vien Van, Uriel Levy, Yang Jiancai, and Zhanghua Han

DOI: 10.1364/PRJ.456260 Received 14 Feb 2022; Accepted 10 May 2022; Posted 16 May 2022  View: PDF

Abstract: The phenomenon of bound state in the continuum (BIC) with infinite quality factor and lifetime has emerged in recent years in photonics as a new tool of manipulating light-matter interactions. However, most of the investigated structures only support BIC or quasi BIC (QBIC) resonances at very few discrete positions in the ω~k space, restricting their applications in many fields where random or more input frequencies than the number of supported QBIC resonances are required. In this work, we demonstrate that a new set of QBIC resonances can be supported by making use of a special composite grating consisting of two ridge arrays with the same period and zero-approaching ridge width difference on a slab waveguide. These BIC resonances are distributed continuously over a broad band along a line in the ω~k space and can thus be considered as one-dimensional BICs. With a slight increase of the width difference, these BICs will switch to quasi-BIC modes and it is possible to choose arbitrarily any frequencies on the dispersion line to achieve significantly enhanced light-matter interactions, facilitating many applications where multiple input wavelengths are required, e.g. sum or difference frequency generations in nonlinear optics.

Self-Driven Highly Responsive PN Junction InSe Heterostructure Near-Infrared Light Detector Invited

Chandraman Patil, Chaobo Dong, Hamed Dalir, Sergiy Krylyuk, Albert Davydov, Volker Sorger, Hao Wang, Huairuo zhang, and Elham Heidari Movahhed Nouri

DOI: 10.1364/PRJ.441519 Received 27 Aug 2021; Accepted 10 May 2022; Posted 17 May 2022  View: PDF

Abstract: Photodetectors converting light signals into detectable photocurrents are ubiquitously in use today. To improve the compactness and performance of next-generation devices and systems, low dimensional materials provide rich physics to engineering the light-matter interaction. Photodetectors based on two-dimensional (2D) material van der Waals heterostructures have shown high responsivity and compact integration capability, mainly in the visible range due to their intrinsic bandgap. The spectral region of near-infrared (NIR) is technologically important featuring many data communication and sensing applications. While some initial NIR 2D material-based detectors have emerged, demonstrating doping-junction-based 2D material photodetectors with the capability to harness the charge-separation photovoltaic-effect are yet outstanding. Here, we demonstrate a 2D p–n van der Waals heterojunction photodetector constructed by vertically stacking p-type and n-type few-layer indium selenide (InSe) 2D flakes. This heterojunction charge-separation-based photodetector shows a three-fold enhancement in responsivity at near-infrared spectral region (980 nm) as compared to a photoconductor detector based on p- or n-only doped regions, respectively. We show, that this junction device exhibits self-powered photodetection operation and hence enables few pA-low dark currents, which is about 3-4 orders of magnitude more efficient than state-of-the-art foundry-based devices. Such capability opens doors for small signal-to-noise environments and low photon-count detectability without having to rely on external gain. We further demonstrate millisecond response rates in this sensitive zero-bias voltage regime. Such sensitive photodetection capability in the technologically relevant NIR wavelength region at low form factors holds promise for several applications including wearable biosensors, 3D sensing, and remote gas sensing.

Ultra-wide varifocal imaging with selectable region of interest capacity using Alvarez lenses actuated by dielectric elastomer

Qun Hao, CHUANXUN CHEN, jie CAO, Zhikuo Li, and Yang Cheng

DOI: 10.1364/PRJ.455331 Received 31 Jan 2022; Accepted 09 May 2022; Posted 09 May 2022  View: PDF

Abstract: A varifocal lens is an important part of optical systems with applications in biomedicine, photography, smartphone, and virtual reality. A remarkable feature of Alvarez lenses is that a wide focal length tuning range can be achieved using lateral displacement rather than commonly-used axial translation, thus reducing the overall length of varifocal imaging systems. We present here a novel varifocal imaging system based on the Alvarez lenses actuated by dielectric elastomer (DE). The varifocal imaging system is composed of the varifocal component and the scanning component. The large deformation generated by the DE actuators permits lateral displacement of the varifocal component is up to 1.145 mm. The focal length ratio of the proposed varifocal imaging system is up to 30.5 times, where the maximum focal length is 181 mm and the minimum focal length is 5.94 mm. By applying different voltages on four quadrants, the scanning component allows the varifocal component to move in different directions and endows the varifocal component with a selectable region of interest imaging capability. The rise and fall times of the proposed system are 160 ms and 210 ms, respectively. The imaging resolution is approximately 181 lp/mm. The system developed in the current study has the potential to be used in consumer electronics, endoscopy, and microscopy in the future.

Nearly 70-Gbit/s NRZ-OOK Encoding of Dual-mode 850-nm VCSEL with High In-doped and small Zn-diffused Emission Area

Gong-Ru Lin, Chih-Hsien Cheng, Hao-chung Kuo, SHAO-YUNG LEE, Xin Chen, CHIA-HSUAN Wang, Ming-Jun Li, Yu-Ming Huang, WEI-TA HUANG, and Dong Yang

DOI: 10.1364/PRJ.457506 Received 03 Mar 2022; Accepted 08 May 2022; Posted 09 May 2022  View: PDF

Abstract: By pre-emphasized encoding a dual-mode 850-nm vertical-cavity surface-emitting laser (VCSEL), the nearly 70-Gbit/s on-off keying (OOK) transmission performance is performed for the ultrafast data link. This VCSEL is designed with a new structural configuration including 6-µm oxidized aperture and 4-µm Zn-diffused emission aperture, which exhibits dual-mode lasing with a threshold current of 0.75 mA, a non-saturated power of 2.2 mW at 8 mA, and a differential quantum efficiency of 0.38 under a lensed OM4 multimode fiber (MMF) coupling scheme. In particular, the high indium (In) dopant density in the quantum well increases its differential gain coefficient to up-shift the relaxation oscillation frequency, which effectively broadens the modulation bandwidth to high-speed data transmission. For the back-to-back transmission, the VCSEL coupled with a lensed OM4-MMF (1-m) for short-reach link reveals an NRZ-OOK transmission at 66 and 69 Gbit/s with corresponding bit-error ratio (BER) of 5.9E−10 and 1E−5 for error-free decoding after forward-error correction. When employing graded-index single-mode fiber (GI-SMF) with 100-m length as the transmission segment, the VCSEL linked to the GI-SMF connected with a lensed OM4-MMF (1-m) collimator can provide the pre-emphasized NRZ-OOK transmission at 51 Gbit/s with a BER of 4.5E−10 and SNR of 14.1 dB.

On-chip path encoded photonic quantum Toffoli gate

Meng Li, Chu Li, yang chen, Lantian Feng, Linyu Yan, Qian Zhang, Jueming Bao, Bi-Heng Liu, Xifeng Ren, Jianwei Wang, Shufeng Wang, Yunan Gao, Xiaoyong Hu, Qihuang Gong, and Yan Li

DOI: 10.1364/PRJ.452539 Received 03 Jan 2022; Accepted 08 May 2022; Posted 09 May 2022  View: PDF

Abstract: The quantum Toffoli gate is one of the most important three-qubit gates, but it is challenging to construct a chip according to the complicated traditional circuit. Using the optimized 3D configuration with an overpass waveguide to reduce the circuit complexity, we successfully fabricate an on-chip path encoded photonic quantum Toffoli gate enabled by the 3D capability of the femtosecond laser direct writing (FLDW) for the first time, whose fidelity is higher than 85.5%. Furthermore, a path encoded four-qubit Controlled-Controlled-Controlled NOT gate is written to confirm the scalability of this resource-saving technique. This work paves the way for the FLDW of more complex and powerful photonic quantum computation chips.

Stronger Hardy-Like Proof of Quantum Contextuality

Yongnan Li, Wen-Rong Qi, Jie Zhou, Ling-Jun Kong, Zhen Xu, huixian meng, Rui Liu, Zhou-Xiang Wang, Chenghou Tu, Adan Cabello, Jing-Ling Chen, and Hui-Tian Wang

DOI: 10.1364/PRJ.452704 Received 30 Dec 2021; Accepted 04 May 2022; Posted 09 May 2022  View: PDF

Abstract: A Hardy-like proof of quantum contextuality is a compelling way to see the conflict between quantum theory and noncontextual hidden variables(NCHV), as the latter predict that a particular probability must be zero, while quantum theory predicts a nonzero value. For the existing Hardy-like proofs, the success probability tends to 1/2 when the number of measurement settings n goes to infinity. It means the conflict between the existing Hardy-like proof and NCHV theory is weak, which is not conducive to experimental observation. Here we advance the study of stronger Hardy-like proof of quantum contextuality, whose success probability isalways higher than the previous ones generated from a certain n-cycle graphs. Furthermore, the success probability tends to 1 when n goes to infinity. We perform the experimental test of the Hardy-like proof in the simplest case of n = 7 by using a four-dimensional quantum system encoded in the polarization and orbital angular momentum of single photons. The experimental result agrees with the theoretical prediction within experimental errors. In addition, by starting from our Hardy-like proof, one can establish the stronger noncontextuality inequality, for which the quantum-classical ratio is higher with the same n, which provide a new method to construct some optimal noncontextuality inequalities. Our results offer a way for optimizing and enriching exclusivity graphs, helping to explore more abundant quantum properties.

Tunable Non-Hermiticity through Reservoir Engineering

Xin Meng, Yanhong Xiao, Wei Yi, Xingda Lu, Zhiwei Hu, Xichang Zhang, Ying Hu, Wanxia Cao, and Li HaoWei

DOI: 10.1364/PRJ.450166 Received 01 Dec 2021; Accepted 04 May 2022; Posted 04 May 2022  View: PDF

Abstract: We experimentally demonstrate tunable non-Hermitian coupling in an atomic-vapour cell where atomic coherences in different optical channels are dissipatively coupled through atomic motion. Introducing a far-detuned light wall in the reservoir between the optical channels, we decorate the inter-channel coupling term so that it can be switched from dissipative to coherent. The tunable non-Hermiticity is then confirmed through measurements of the inter-channel light transport where the light-wall-induced phase shift is directly probed. Based on the tunable non-Hermiticity, we further discuss an exemplary scheme in which our setup can serve as a building block for the experimental study of exotic non-Hermitian criticality.

Advanced hybrid plasmonic nano-emitters using smart photopolymer

Dandan GE, Renaud Bachelot, Safi Jradi, Christophe Couteau, Ali Issa, and Sylvie Marguet

DOI: 10.1364/PRJ.455712 Received 09 Feb 2022; Accepted 03 May 2022; Posted 04 May 2022  View: PDF

Abstract: The integration of nano-emitters into plasmonic devices with spatial control and nanometer precision has become a great challenge. In this paper, we report on the use of a smart polymer for selectively immobilizing nano-emitters on specific preselected sites of gold nanocubes (GNC). The cunning use of the polymer is twofold. First, it records both the selected site and the future emitters-GNC distance through plasmon-assisted photopolymerization. Second, because the polymer is chemically functionalized, it makes it possible to attach the nano-emitters right at the preselected polymerized sites which subsequently “recognize” the nano-emitters to get attached. Since the resulting active medium is a spatial memory of specific plasmonic modes, it is anisotropic, making the hybrid nanosources sensitive to light polarization. The ability to adjust their statistical average lifetime by controlling the thickness of the nanopolymer is demonstrated on two kinds of nano-emitters coupled to GNC: doped polystyrene nanospheres and semiconductor colloidal quantum dots.

Surface acoustic wave photonic filters with a single narrow radio-frequency passband in standard silicon on insulator

Moshe Katzman, Maayan Priel, Inbar Shafir, Saawan Kumar Bag, Dvir Munk, Naor Inbar, Moshe Feldberg, Tali Sharabani, Avi Zadok, MATAN SLOOK, and Leroy Dokhanian

DOI: 10.1364/PRJ.457340 Received 01 Mar 2022; Accepted 03 May 2022; Posted 23 May 2022  View: PDF

Abstract: Integrated microwave photonic filters become increasingly important for signal processing within advanced wireless and cellular networks. Filters with narrow transmission passbands mandate long time delays, which are difficult to accommodate within photonic circuits. Long delays may be obtained through slow moving acoustic waves instead. Input radio frequency information can be converted from one optical carrier to another via surface acoustic waves and filtered in the process. However, the transfer functions of previously reported devices consisted of multiple periodic passbands, and the selection of a single transmission band was not possible. In this work, we demonstrate surface acoustic wave, silicon-photonic filters of microwave frequency with a single transmission passband. The filters response consists of up to 32 tap coefficients, and the transmission bandwidth is only 7 MHz. The results extend the capabilities of integrated microwave photonics in the standard silicon on insulator platform.

Lanthanide-doped nanocrystals in high-Q microtoroids for stable on-chip white-light laser

Qinghai Song, Limin JIN, Zhuo Liu, Yuqi Zhang, Yunkai Wu, Yilin Liu, Huachun Deng, and Shumin Xiao

DOI: 10.1364/PRJ.456381 Received 25 Feb 2022; Accepted 02 May 2022; Posted 04 May 2022  View: PDF

Abstract: The plentiful energy states of lanthanide (Ln3+)-doped nanomaterials make them very promising for on-chip integrated white-light lasers. Despite the rapid progresses, the Ln3+-based white up-conversion emission are strongly restricted by their low up-conversion quantum efficiency and the color stability. Herein, we combine the CaF2:Yb35Tm1.5Er0.5 nanocrystals and the high-Q microtoroids, and experimentally demonstrate the chip-integrated stable white-light laser. By optimizing the sizes, density, and distributions of Ln3+-doped nanocrystals, the Q factors of Ln3+-doped microtoroids are maintained as high as 5×10⁵. The strong light matter interaction in high-Q microtoroids greatly enhance the up-conversion emission and dramatically reduce the laser thresholds at 652 nm, 545 nm, and 475 nm to similarly low values (1.89-2.10 mJ cm-2). Consequently, robust white-light microlaser has been experimentally achieved from a single microtoroid. This research has paved a solid step towards the chip-scale integrated broadband microlasers.

Deep reinforcement with spectrum series learning control for a mode-locked fiber laser

Zhan Li, Shuaishuai Yang, Qi Xiao, Tianyu Zhang, Yong Li, Lu Han, Dean Liu, Xiaoping Ouyang, and Jianqiang Zhu

DOI: 10.1364/PRJ.455493 Received 04 Feb 2022; Accepted 29 Apr 2022; Posted 29 Apr 2022  View: PDF

Abstract: A spectrum series learning-based model is presented for mode-locked fiber laser state searching and switching. The mode-locked operation search policy is obtained by our proposed algorithm that combines deep reinforcement learning (DRL) and long short-term memory (LSTM) networks. Numerical simulations show that the dynamic features of the laser cavity can be obtained from spectrum series, which greatly improves the efficiency of mode-locked search. The switch of the mode-locked state is realized by a predictive neural network that controls the pump power. In the experiments, the proposed algorithm uses an average of only 690 ms to obtain a stable mode-locked state, which is one order of magnitude less than the traditional method. And the maximum search steps of the algorithm is 47 in the 16⁰C - 30⁰C temperature environment. The pump power prediction error is less than 2 mW, which ensures precise laser locking on multiple operating states. This proposed technique paves the way for a variety of optical systems that require fast and robust control.

Metalens based stereoscopic microscope

Yong Long, Jianchao Zhang, Zhihao Liu, Weibin Feng, Songming Guo, QIAN SUN, Qinfei Wu, Xiang-Yang Yu, Jianying Zhou, Emiliano Martins, Haowen Liang, and Juntao Li

DOI: 10.1364/PRJ.456638 Received 21 Feb 2022; Accepted 29 Apr 2022; Posted 29 Apr 2022  View: PDF

Abstract: Stereoscopic microscopy is a promising technology to obtain three-dimensional microscopic images. Such microscopes are based on the parallax effect, and as such require two lenses to focus at two different points. Geometrical constraints, however, restrict their numerical apertures to about 0.2, thus limiting the system’s resolution. Higher numerical apertures (~ 0.35) can be achieved with designs using only one bulk lens, but such systems are ~10 times more costly than the conventional ones. Thus, there is a pressing need for alternative solutions to improve the resolution of stereoscopic systems. Here, we show that high-resolution and low-cost stereoscopic systems can be obtained using birefringent single layer metalenses. We design and fabricate a birefringent metalens operating at 532 nm with a NA as high as 0.4. The metalens is then used to demonstrate high resolution stereoscopic imaging of biological samples. The microscopic images are further displayed and perceived vividly in an autostereoscopic display. Our demonstration paves the way to a new strategy to achieve high-resolution and low-cost stereoscopic microscopes.

Nonlinear quantum spectroscopy with Parity-Time symmetric integrated circuits

Pawan Kumar, Sina Saravi, Thomas Pertsch, Frank Setzpfandt, and Andrey Sukhorukov

DOI: 10.1364/PRJ.450410 Received 06 Dec 2021; Accepted 26 Apr 2022; Posted 26 Apr 2022  View: PDF

Abstract: We propose a novel quantum nonlinear interferometer design that incorporates a passive PT symmetric coupler sandwiched between two nonlinear sections where signal-idler photon pairs are generated. ThePT-symmetry enables efficient coupling of the longer-wavelength idler photons and facilitates the sensing of losses in the second waveguide exposed to analyte under investigation, whose absorption can beinferred by measuring only the signal intensity at a shorter wavelength where efficient detectors are readily available. Remarkably, we identify a new phenomenon of sharp signal intensity fringe shift at criticalidler loss values, which is distinct from the previously studied PT-symmetry breaking. We discuss how such unconventional properties arising from quantum interference can provide a route to enhancing thesensing of analytes and facilitate broadband spectroscopy applications in integrated photonic platforms.

Ultra-sharp silicon multimode waveguides bends based on the double free-form curves

shangsen sun, zhiqiang yang, juanli wang, runsen zhang, fengchun zhang, Ning Zhu, Lei Wan, and Zhaohui Li

DOI: 10.1364/PRJ.445529 Received 18 Oct 2021; Accepted 24 Apr 2022; Posted 25 Apr 2022  View: PDF

Abstract: Mode-division multiplexing (MDM) can greatly improve the capacity of information transmission. The multimode waveguide bend (MWB) with small size and high performance is of great significance for the on-chip MDM integrated system. In this paper, the MWB with high performance based on the double free-form curves (DFFC) is proposed and realized. The DFFC is a combination of a series of arcs optimized by the inverse design method. The fabrication of this MWB only needs one-step lithography and plasma etching and has a large fabrication tolerance. The MWBs with effective radii of 6 μm and 10 μm are designed to support three modes and four modes, respectively. The proposed method gives the best overall performance considering both the effective bending radius and transmission efficiency. The fabricated MWB with four mode channels has low excess losses and crosstalks below −21 dB in the wavelength range from 1520 to 1580 nm. It is expected that this design can play an important role in promoting the dense integration of multimode transmission systems.

Neural network-based surrogate model for inverse design of metasurfaces

Shuqing Chen, guoqing jing, Peipei Wang, Haisheng Wu, Jianjun Ren, Zhiqiang Xie, Junmin Liu, Huapeng Ye, Ying Li, and Dianyuan Fan

DOI: 10.1364/PRJ.450564 Received 06 Dec 2021; Accepted 24 Apr 2022; Posted 25 Apr 2022  View: PDF

Abstract: Metasurfaces composed of spatially arranged ultrathin subwavelength elements are promising photonic devices for manipulating optical wavefronts, with potential applications in holography, metalens, and multiplexing communications. Finding microstructures that meet light modulation requirements is always a challenge in designing metasurfaces, where parameter sweep, gradient-based inverse design, and topology optimization are the most commonly used design methods in which the massive electromagnetic iterations require the design computational cost and are sometimes prohibitive. Herein, we propose a fast inverse design method that combines a physical-based neural network surrogate model (NNSM) with a optimization algorithm. The NNSM, which can generate an accurate electromagnetic response from the geometric topologies of the meta-atoms, is constructed for electromagnetic iterations, and the optimization algorithm is used to search for the on-demand meta-atoms from the phase library established by the NNSM to realize an inverse design. This method addresses two important problems in metasurface design: fast and accurate electromagnetic wave phase prediction and inverse design through a single phase-shift value. As a proof-of-concept, we designed an orbital angular momentum (de)multiplexer based on a phase-type metasurface, and 200 Gbit/s quadrature-phase shift-keying signals were successfully transmitted with a bit error rate approaching 1.67 × 10-6. Because the design is mainly based on a optimization algorithm, it can address the “one-to-many” inverse problem in other micro/nano devices such as integrated photonic circuits, waveguides, and nano-antennas.

Adaptive optics wavefront correction using a damped transpose matrix of the influence function

Boyu Gu and Yuhua Zhang

DOI: 10.1364/PRJ.452364 Received 29 Dec 2021; Accepted 24 Apr 2022; Posted 25 Apr 2022  View: PDF

Abstract: To assess the performance of adaptive optics and predict an optimal wavefront correction, we built a wavefront reconstructor using a damped transpose of the influence function matrix. Using an integral control strategy, we tested this reconstructor with 3 different deformable mirrors in an experimental system and in an adaptive optics scanning laser ophthalmoscope. Testing results proved that this reconstructor could ensure a stable and precise correction for wave aberration in comparison to a conventional optimal reconstructor formed by the inverse of the influence function matrix. This method provides a useful tool for AO system testing, evaluation, and optimization.

Evanescent Waveguide Lab-on-Chip for Optical Biosensing in Food Quality Control

Alessio Buzzin, Rita Asquini, Domenico Caputo, and Giampiero de Cesare

DOI: 10.1364/PRJ.454288 Received 20 Jan 2022; Accepted 20 Apr 2022; Posted 20 Apr 2022  View: PDF

Abstract: Optical biosensing systems are commonly developed assembling a source, a light-sample interaction area and a detector as distinct stand-alone elements. We present a compact, inexpensive and easy-to-use glass chip which monolithically integrates both the interaction and detection elements in a \unit[1]{cm$^{2}$} overall surface. The device working principle is based on the evanescent wavelight interaction with the complex refractive index of a liquid mixture, being the index influenced by the mixture’s physical and chemical features. We describe the manufacture of a prototype able to perform investigations on food quality and the following tests on the detection of fat content in milk. Theoretical investigations are reported as well as measures performed on samples in the green spectrum. A sensitivity of about \unit[139]{fA/(g/dL)} and a limit of detection of \unit[14]{ppm} have been achieved, better than current commercial devices.

Spin-decoupled geometric metasurface for polarization sythesis and multidimensional multiplexing of terahertz converged vortices

Yang Zhu, Binbin Lu, Zhiyuan Fan, Fuyong Yue, XiaoFei Zang, Alexei Balakin, Alexander Shkurinov, Yiming Zhu, and Songlin Zhuang

DOI: 10.1364/PRJ.455459 Received 03 Feb 2022; Accepted 20 Apr 2022; Posted 21 Apr 2022  View: PDF

Abstract: The investigation of converged twisted-beams with a helical phase structure has a remarkable impact on both fundamental physics and practical applications. Geometric metasurfaces consisting of individually orientated metal/dielectric meta-atoms provide an ultracompact platform for generating converged vortices. However, spin-locking in the geometric phase response of left-handed and right-handed circularly polarized incident beams hinders the independent operation on topological charges between the two helical components. Here we propose and experimentally demonstrate an approach to design terahertz spin-decoupled geometric metasurfaces that can generate helicity-independent converged vortices with homogeneous polarization states by the superposition of two orthogonal helical-vortices with identical topological charges. Furthermore, the multiplexing of polarization-rotatable multiple vortices on multiple dimensions, i.e. on both the longitudinal and transverse directions, and vortex with an extended focal depth are confirmed by embedding the polarization modulation into the spin-decoupled geometric metasurfaces. The demonstrated approach provides a new way to break the symmetric restriction of the geometric phase and expands the design dimension, enabling new applications of geometric metasurface devices in polarization optics, twisted-beam related image and edge dection, high capacity optical communciation, and quantum information processing, to name a few.

Total polarization conversion using subwavelength laser-induced periodic surface structures on stainless steel

Mahmoud Elshorbagy, Luis Miguel Sanchez-Brea, Jeronimo Buencuerpo, Jesus del Hoyo, Ángela Soria-García, Verónica Pastor-Villarrubia, Alejandro San Blas, Ainara Rodriguez, Santiago Olaizola, and Javier Alda

DOI: 10.1364/PRJ.454451 Received 25 Jan 2022; Accepted 18 Apr 2022; Posted 06 May 2022  View: PDF

Abstract: Stainless steel is a basic raw material in industry. It can be customized by generating laser-induced periodic surface structures (LIPSS) as subwavelength gratings. Here, we present the capabilities of LIPSS on stainless steel to modify the polarization state of the reflected radiation at the infrared . These structures have been modeled using the finite element method and fabricated by femtosecond laser processing. The Stokes parameters have been obtained experimentally and a model for the shape has been used to fit the simulated Stokes values to the experimental data. The birefringence of the LIPSS is analyzed to explain how they modify the polarization state of the incoming light. We find the geometry of the subwavelength grating that makes it work as an optical retarder that transforms a linearly polarized light into a circularly polarized wave. Also, the geometrical parameters of the LIPSS are tuned to absorb selectively one of the components of the incoming light, becoming a linear axial polarizer. An appropriate selection of the geometrical parameters and orientation of the fabricated LIPSS makes possible to obtain an arbitrary pure polarization state when illuminated by any other pure polarization state. The overall reflectance of these transformations reaches values up to 60% with respect to the incident intensity, that is the same reflectivity obtained for non nanostructured stainless steels flat surfaces.

Fully integrated hybrid microwave photonic receiver

Jiachen Li, Sigang Yang, Hongwei Chen, Xingjun Wang, Minghua Chen, and Weiwen Zou

DOI: 10.1364/PRJ.452631 Received 11 Jan 2022; Accepted 12 Apr 2022; Posted 12 Apr 2022  View: PDF

Abstract: Microwave photonic receivers are the promising candidate desired for breaking the bandwidth limitation of traditional radio-frequency (RF) receivers. To further balance the performance superiority with the requirements on size, weight, and power consumption (SWaP), the implementation of integrated microwave photonic microsystems has been considered as an upgrade path. However, up to now, chip-scale fully integrated microwave photonic receivers have not been reported due to the limitation of material platforms. In this paper, we report a fully integrated hybrid microwave photonic receiver (FIH-MWPR) by comprising the indium phosphide (InP) laser chip and the monolithic silicon-on-insulator (SOI) photonic circuit into the same substrate based on the low-coupling-loss micro-optics method. Benefiting from the integration of all optoelectronic components, the packaged FIH-MWPR exhibits a compact volume of 6 cm^3 and low power consumption of 1.2 W. The FIH-MWPR supports a wide operation bandwidth from 2 to 18 GHz. Besides, its RF-link performance to down-convert RF signals to the intermediate frequency is experimentally characterized by measuring the link gain, the noise figure, and the spurious-free dynamic range metrics across the whole operation frequency band. Moreover, we have utilized it as a de-chirp receiver to process the broadband linear frequency-modulated (LFM) radar echo signals at different frequency bands (S-, C-, X-, and Ku-bands) and successfully demonstrated its high-resolution ranging capability. To the best of our knowledge, this is the first realization of chip-scale broadband fully integrated microwave photonic receiver, which is expected to be an important step in demonstrating the feasibility of all-integrated microwave photonic microsystems oriented to miniaturized application scenarios.

Passivation of Degradation Path Enable High Performance Perovskite Nanoplatelet Lasers with High Operational Stability

Guohui Li, Huihui Pi, Yanfu wei, Boling Zhou, Ya Gao, Rong Wen, Yuying Hao, Han Zhang, Beng S. Ong, and Yanxia Cui

DOI: 10.1364/PRJ.452620 Received 30 Dec 2021; Accepted 12 Apr 2022; Posted 12 Apr 2022  View: PDF

Abstract: MAPbI3 perovskite has attracted widespread interests for developing low-cost near infrared semiconductor gain media. However, it faces the instability issue under operation conditions, which remains a critical challenge. It is found that the instability of the MAPbI3 nanoplatelet laser comes from the thermal-induced-degradation progressing from the surface defects towards neighboring regions. By using PbI2 passivation, the defect-initiated degradation is significantly suppressed and the nanoplatelet degrades in a layer-by-layer way, enabling the MAPbI3 laser sustain for 4500 s (2.7×10^7 pulses), which is almost 3 times longer than that of the nanoplatelet laser without passivation. Meanwhile, the PbI2 passivated MAPbI3 nanoplatelet laser with the nanoplatelet cavity displaying a maximum quality factor up to ~7800, the highest reported for all MAPbI3 nanoplatelet cavities. Furthermore, a high stability MAPbI3 nanoplatelet laser that can last for 8500 s (5.1×10^7 pulses) is demonstrated based on a dual passivation strategy, by retarding the defect-initiated degradation and surface-initiated degradation, simultaneously. This work provides in-depth insights for understanding the operating degradation of perovskite lasers and the dual passivation strategy paves the way for developing high stability near infrared semiconductor laser media.

Silicon nitride passive and active photonic integrated circuits: trends and prospects

Chao Xiang, Warren Jin, and John Bowers

DOI: 10.1364/PRJ.452936 Received 05 Jan 2022; Accepted 11 Apr 2022; Posted 12 Apr 2022  View: PDF

Abstract: The use of silicon nitride in integrated photonics has rapidly progressed in recent decades. Ultra-low-loss waveguides based on silicon nitride are a favorable platform for the research and application of nonlinear photonics and microwave photonics to a wide variety of fields, including precision metrology, communications, sensing, imaging, navigation, computation, and quantum physics. In recent years, the integration of Si and III-V materials has enabled new large-scale, advanced silicon nitride based photonic integrated circuits with versatile functionality. In this perspective article, we review current trends and the state-of-the-art in silicon nitride based photonic devices and circuits. We highlight the hybrid and heterogeneous integration of III-V with silicon nitride for electrically pumped soliton microcomb generation, and ultra-low-noise lasers with fundamental linewidth in the tens-of-mHz range. We also discuss several ultimate limits and challenges of silicon nitride based photonic device performance, and provide routes and prospects for future development.

Extremely narrow resonant linewidths in metal-dielectric heterostructures

Jie Zheng, Jinfeng Zhu, and Yang Zhi-Lin

DOI: 10.1364/PRJ.458049 Received 10 Mar 2022; Accepted 06 Apr 2022; Posted 07 Apr 2022  View: PDF

Abstract: The high-quality factors (Q factors) of the resonators having the characteristic of narrow SPR linewidths are extremely significant for SERS, optical sensors, imaging, and color filter. Unfortunately, the extensive researches about narrowing SPR linewidths are mainly based on noble metal nanostructures which are restricted to intrinsic loss. Here, heterostructures consisting of metal and dielectric metaphotonics experimentally are designed and fabricated the for elaborating SPR linewidths. The results demonstrate that the SPR linewidths can be narrowed by down to 66.7% with respect to that of aluminum nanostructures. The resonant linewidths are directly shrinked benefiting from the interaction between low loss in semiconductor nanostructures and electromagnetic confinement in the metal counterparts. Meanwhile, the resonant wavelength governed on heterostructures configurations expand from 600 nm to 930 nm. This work will pave an avenue toward controlling resonant linewidths for numerous applications based on metal-dielectric heterostructures.

Spectrally multiplexed indistinguishable single photon generation at telecom-band

Qiang Zhou, Hao Yu, Chenzhi yuan, Ruiming Zhang, Zichang Zhang, Hao Li, You WANG, Guangwei Deng, Lixing YOU, Hai-Zhi Song, Zhiming Wang, and Guang-can Guo

DOI: 10.1364/PRJ.450731 Received 15 Dec 2021; Accepted 02 Apr 2022; Posted 04 Apr 2022  View: PDF

Abstract: Heralded single photon source (HSPS) intrinsically suffers from the trade-off between the heralded single photon rate and the purity of single photon. To break through this trade-off, one can apply multiplexing technology in different degrees of freedom that significantly improves the performance of HSPS. Here, we propose a chip-scale HSPS at 1.5 μm telecom-band by employing spectral multiplexing and active feed-forward spectral manipulating, and demonstrate a proof-of-principle experiment with discrete fiber-based components. With three spectral modes multiplexed, our experimental results show that the spectral multiplexing improves the heralded single photon rate by near three-fold while keeping the g(²)(0) as low as 0.0006±0.0001 at single photon rate of 3.1 kHz, reaching the highest single photon purity ever reported in multiplexing. By measuring the joint spectral intensity, we show that the spectral multiplexing and feed-forward control effectively erase the frequency correlation of photon-pairs. Moreover, we implement the Hong-Ou-Mandel interference between the spectrally multiplexed single photons and photons from an independent weak coherent source, which indicates that the multiplexed single photons are highly indistinguishable after the spectral manipulation. Our results pave a way for on-chip scalable and high performance HSPS with spectral multiplexing towards deterministic single photon emission.

Monolithic GaAs/Si V-groove depletion-type optical phase shifters integrated in a 300mm Si photonics platform

YOUNGHYUN KIM, DIDIT YUDISTIRA, Bernardette Kunert, MARINA BARYSHNIKOVA, REYNALD ALCOTTE, Cenk Ibrahim Ozdemir, SangHyeon Kim, Sebastien Lardenois, Peter Verheyen, Joris Van Campenhout, and Marianna Pantouvaki

DOI: 10.1364/PRJ.451821 Received 21 Dec 2021; Accepted 30 Mar 2022; Posted 31 Mar 2022  View: PDF

Abstract: We demonstrate monolithically integrated n-GaAs/p-Si depletion-type optical phase shifters fabricated on a 300mm wafer-scale Si photonics platform. We measured the phase shifter performance using Mach-Zehnder modulators with the GaAs/Si optical phase shifters in both arms. Modulation efficiency of VπL as low as 0.3 V·cm has been achieved, which is much lower compared to a carrier-depletion type Si optical phase shifter with pn-junction. While propagation loss is relatively high at ~ 6.5 dB/mm, the modulator length can be reduced by the factor of ~ 4.2 for the same optical modulation amplitude of a Si reference Mach-Zehnder modulator, owing to the high modulation efficiency of the shifters.

Simultaneous multiple timescale imaging for high-speed accelerometry

Vassily Kornienko, David Andersson, Mehdi Stiti, Jonas Ravelid, Simon Ek, Edouard Berrocal, Andreas Ehn, and Elias Kristensson

DOI: 10.1364/PRJ.451108 Received 13 Dec 2021; Accepted 29 Mar 2022; Posted 02 May 2022  View: PDF

Abstract: Fast transient events, such as the disintegration of liquid bodies or chemical reactions between radical species, involve various processes that may occur at different timescales. Currently, there are two alternatives for monitoring such events: burst- or high-speed imaging. Burst imaging at ultra-high speeds (~100 MHz - THz) allows the fastest processes to be captured but only for a narrowly confined period of time and under the condition that the onset can be predicted. To monitor long lasting events with existing high-speed imaging technology, the frame rate must be reduced (~ kHz - 1 MHz) and thus processes occurring on sub-microsecond timescales cannot be observed. To date, no imaging technology is capable of visualizing detailed sub-microsecond dynamics over a long period of time. In this manuscript we present a solution to this technological gap by combining multiplexed imaging with high-speed sensor technology resulting in temporally resolved image series at two simultaneous timescales. We demonstrate its unique capability of tracking structures at MHz burst rates over a long time by, for the first time, extracting 2D accelerometry data acting upon liquid bodies at kHz frame-rates.

Experimental Quantum Simulation of Dynamic Localization on Curved Photonic Lattices

Hao Tang, Tian-Yu Wang, Zi-Yu Shi, Zhen Feng, Yao Wang, Jun Gao, Zhi-Qiang Jiao, Zhan-Ming Li, Yijun Chang, Yi-Lin Yang, Wen-Hao Zhou, Yong-Heng Lu, Ruo-Jing Ren, Lu-Feng Qiao, and Xianmin Jin

DOI: 10.1364/PRJ.439637 Received 13 Jan 2022; Accepted 22 Mar 2022; Posted 25 Mar 2022  View: PDF

Abstract: Dynamic localization, which originates from the phenomena of particle evolution suppression under an externally applied ac electric field, has been simulated by suppressed light evolution in periodically-curved photonic arrays. However, experimental studies on their quantitative dynamic transport properties and application for quantum information processing are rare. Here we fabricate one-dimensional and hexagonal two-dimensional arrays, both with sinusoidal curvature. We successfully observe the suppressed single-photon evolution patterns, and for the first time measure the variances to study their transport properties. For one-dimensional arrays, the measured variances match both the analytical electric field calculation and the quantum walk Hamiltonian engineering approach. For hexagonal arrays, as anisotropic effective couplings in four directions are mutually dependent, the analytical approach suffers, while quantum walk conveniently incorporates all anisotropic coupling coefficients in the Hamiltonian and solves its exponential as a whole, yielding consistent variances with our experimental results. Furthermore, we implement a nearly complete localization to show that it can preserve both the initial injection and the wave-packet after some evolution, acting as a memory of a flexible time scale in integrated photonics. We demonstrate a useful quantum simulation of dynamic localization for studying their anisotropic transport properties, and a promising application of dynamic localization as a building block for quantum information processing in integrated photonics.

Modulation of plasmonic relaxation damping by surface phonons

Kuntal Barman, Syu-Cin Ma, and JianJang Huang

DOI: 10.1364/PRJ.455665 Received 07 Feb 2022; Accepted 19 Mar 2022; Posted 21 Mar 2022  View: PDF

Abstract: We study experimentally the effect of amplitude varying surface acoustic waves on localized surface plasmons (LSP), which unveils exceptional properties of plasmon-phonon interaction with promising applications in future tunable photonic devices. Gold nanoparticles are deposited on an X-cut LiNbO3 to generate plasmonic oscillation, and an interdigital transducer is fabricated to create surface acoustic wave pulses. The interaction between amplitude varying mechanical wave and plasmonic oscillation affects different plasmon dynamics and relaxation gradients, leading to a systematic change in LSP absorption. We also demonstrated the effect of polarized light on the device, providing a unique characteristic to explore the manipulation process effectively.

Generalized Robust Training Scheme using Genetic Algorithm for Optical Neural Networks with Imprecise Components

Rui Shao, Gong Zhang, and Xiao Gong

DOI: 10.1364/PRJ.449570 Received 03 Dec 2021; Accepted 18 Mar 2022; Posted 18 Mar 2022  View: PDF

Abstract: One of the pressing issues for optical neural networks (ONNs) is the performance degradation introduced by parameter uncertainties in practical optical components. Hereby, we propose a novel two-step off-chip training scheme to configure phase shifts in a Mach-Zehnder interferometer (MZI)-based feedforward ONN, where a stochastic gradient descent algorithm followed by a genetic algorithm considering 4 types of practical imprecisions is employed. By doing so, the learning process features fast convergence and high computational efficiency, and the trained ONN is robust to varying degrees and types of imprecisions. We investigate the effectiveness of our scheme by using practical machine learning tasks including Iris and MNIST classifications, showing more than % accuracy improvement after training and comparable accuracy (90.8% in an imprecise ONN with 3 hidden layers and 224 tunable thermal-optic phase shifters) to the ideal one (92.0%).

Anapole-Enhanced Strong Coupling in Heterostructures Beyond the Diffraction Limit

Jing Yu Wang, Wei Min Yang, Guoya Sun, Yonglin He, Peiwen Ren, and Yang Zhi-Lin

DOI: 10.1364/PRJ.453099 Received 06 Jan 2022; Accepted 18 Feb 2022; Posted 18 Feb 2022  View: PDF

Abstract: The light manipulation beyond the diffraction limit plays an invaluable role in modern physics and nanophotonics. In this work, we have demonstrated a strong coupling with a large Rabi splitting of 151 meV between bulk WS2 excitons and anapole modes in the WS2-Si nanodisk heterostructure array with nanoholes as small as 50 nm radius. This result is acquired by introducing anapole modes to suppress radiative losses to confine light into subwavelength volumes and largely spatially overlapping between excitons and strong optical fields. Our work shows that anapole modes may be served as a powerful way to enhance the interaction between light and matter at nanoscales, and should pave an avenue toward high-performance nanostructures optoelectronics applications.