Accepted papers to appear in an upcoming issue
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Dynamics of single-mode nonclassicalities and quantum correlations in the Jaynes-Cummings model
Sriram Akella, Kishore Thapliyal, H Mani, and Anirban Pathak
DOI: 10.1364/JOSAB.459265 Received 23 Mar 2022; Accepted 16 May 2022; Posted 17 May 2022 View: PDF
Abstract: Dynamics of atom-field correlations and single-mode nonclassicalities present in the resonant Jaynes-Cummings model are investigated using negativity and entanglement potential for a set of initial states. The study has revealed the interplay between three different types of nonclassicality present in the model and established that the nonclassicality is continuously exchanged between the field and atom through the atom-field correlations. Further, it is observed that the entanglement potential does not capture all the single-mode nonclassicality and there exists some residual nonclassicality in the reduced single-mode states at the output of the beam splitter which is not captured by the entanglement in which single-mode nonclassicality is quantitatively mapped in Asboth's criterion. Additional layers of beam splitters are added to deplete all the nonclassicality and to reveal that almost all the residual nonclassicality is captured with three layers of beam splitters. Further, the reduced states of the atom and field have zero (non-zero) quantum coherence in the Fock basis when the atom-field correlations are maximum if the field (or atom) has zero (non-zero) quantum coherence initially.
Characterization of Giles Parameters for Extended L band Erbium-Doped Fibers
Sophie LaRochelle, Hanlin Feng, Lixian Wang, Frédéric Maes, and Saber Jalilpiran
DOI: 10.1364/JOSAB.459508 Received 11 Apr 2022; Accepted 14 May 2022; Posted 17 May 2022 View: PDF
Abstract: In this study, we present theoretical and experimental uncertainty analysis of erbium-doped fiber (EDF) characterization to improve performance prediction of erbium-doped fiber amplifiers (EDFAs) in the extended L-band. Through this uncertainty analysis, the optimal EDF lengths for absorption coefficient and emission coefficient characterization are determined to improve precision with a limited number of experimental steps. The uncertainty in the measured clustering ratio is also evaluated based on the uncertainty analysis of absorption and emission coefficients. To verify the accuracy of the Giles parameters determined from the EDF characterization, we compare simulation results, with calculated upper and lower uncertainties for the gain and noise figure (NF), to experimental measurements. The results show that the measured spectral gain and NF match well with the calculated value.
Theoretical analysis of a polarized two-photon Michelson interferometer with broadband chaotic light
Yuchen He, Yu Zhou, JIanbin Liu, Sheng Luo, huabin zheng, Hui Chen, Yan Liu, fuli li, and Zhuo Xu
DOI: 10.1364/JOSAB.459233 Received 23 Mar 2022; Accepted 14 May 2022; Posted 17 May 2022 View: PDF
Abstract: Two-photon interference of broadband chaotic light in a Michelson interferometer is theoretically and numerically studied with two-photon-absorption detector when polarizations are taken into account. Under the scheme of quantum optics, the theoretical analysis is based on two-photon interference and Feynman path integral theory. Two-photon coherence matrix is introduced to calculate the second-order interference pattern. Our researches show that the polarization is another dimension, as well as time and space, to tune the second-order interference pattern in the two-photon interference process. Polarizations can act as switches to manipulate the interference process and may open the gate to some new experimental schemes. The quantum optical vector model is also helpful to understand the physics of second-order interference when the light source is quantum.
Sensitivity enhancement of dispersive cavity with squeezed vacuum light injection
Xiaoyang Chang, hao zhang, Wenxiu Li, Peng Han, Yang Zhou, Anping Huang, and Zhisong Xiao
DOI: 10.1364/JOSAB.458984 Received 21 Mar 2022; Accepted 13 May 2022; Posted 17 May 2022 View: PDF
Abstract: The measurement sensitivity of a cavity could be enhanced for sensing applications in anomalous dispersion condition. In this paper, we find that when injecting a squeezed vacuum light into a dispersive cavity, the sensitivity could be improved further, even beating the Standard Quantum Limit (SQL) at the detuning frequencies via controlling the dispersion condition. It is amazing that normal dispersion is superior to anomalous dispersion in improving the measurement sensitivity in the presence of a squeezed vacuum field. It implies this work could be used to realize high-precision sensing applications.
Raman mediated solitonic pulse compression.
Akash Pradhan, Mrinal Sen, and TANMOY DATTA
DOI: 10.1364/JOSAB.460267 Received 04 Apr 2022; Accepted 13 May 2022; Posted 17 May 2022 View: PDF
Abstract: A comprehensive analysis of Raman mediated solitonic compression of pulses inside silicon nanocrystal embedded slotted photonic crystal waveguide (SPCW) is presented. The ultra-high Raman gain coefficient of the silicon nanocrystal material, being fortified further by the intense optical confinement inside the SPCW, essentially outweighs the contribution of the Kerr in self-phasemodulation (SPM) phenomenon that is responsible for the solitonic propagation of a pulse. This work particularly emphasizes the contribution of Raman nonlinearity in the soliton dynamics, which is however been neglected conventionally, leading to an unprecedented miniaturization in both the operating power and footprint. Spatio-temporal evolution of pulses inside the SPCW has been calculated using nonlinear Schordinger’s equation considering slow-light regime. A compression factor as high as 44.3 is obtained using a 30 µm long SPCW with a peak input power of 8 mW at 1550 nm.
High-efficiency reflective metasurfaces for the terahertz vortex beams generation based on completely independent geometric phase modulations at three frequencies
Yongzhi Cheng, Jiaqi Liu, Fu Chen, Hui Luo, and xiangcheng li
DOI: 10.1364/JOSAB.460153 Received 01 Apr 2022; Accepted 12 May 2022; Posted 17 May 2022 View: PDF
Abstract: One of the considerable disadvantages in the metasurface (MS) is the frequency-dependent behavior, which limits its practical applications to a large extent. To overcome this challenge, a novel reflective MS for vortex beam generation was proposed to work with independent phase control at three distinct terahertz (THz) frequencies. The proposed reflective MS structure can convert the incident circularly polarized (CP) waves into its orthogonal components with reflection coefficients over 0.7 at three different THz resonance frequencies. Based on geometric phase, the full 2π phase shift can be obtained at each frequency by independently rotating three resonator structures of the unit-cell of proposed reflective MS. As proof of demonstrations, by carefully arranging the unit-cell structure of the proposed reflective MS, vortex beams can carry orbital angular momentum (OAM) with topological charge of l = ±1, -2 and -3 at 0.706 THz, 1.143 THz and 1.82 THz have been achieved for the normal incident RCP wave, while the ones with topological charge of l = -3, -2 and -1 have been generated for normal incident LCP wave. The generated reflective vortex beams have a high mode purity that is larger than 85% at 0.706 THz, 84% at 1.143 THz, and 74.7% at 1.82 THz, respectively. Moreover, the designed reflective MS reveals a convenient and low-cost way to generate the vortex beams carrying different/same OAM modes at three different resonance frequencies, and is beneficial to potential application in THz communication.
3D Stokes parameters for vector focal fields
Olga Shoutova, Anatoli Andreev, Sergey Stremoukhov, and Stepan Trushin
DOI: 10.1364/JOSAB.455841 Received 09 Feb 2022; Accepted 11 May 2022; Posted 17 May 2022 View: PDF
Abstract: The study is devoted to the application of the formalism of 3D Stokes parameters to the near-focal structured fields described with Richards-Wolf vector focusing theory. The distribution of the local polarization properties of these fields is characterized in the plane perpendicular to optical axes. The linear polarization parameter was explored, firstly tested in compare of basic loosely and tightly focused Gaussian beams and then, getting deeper insight into its descriptive capabilities, applied to different spatial modes. The distributions of linear polarization parameter and directional cosines of polarization ellipses planes in the transverse plane are presented.
Electromagnetic Response and Optical Properties of Anisotropic CuSbS₂ Nanoparticles
Tapio Ala-Nissila, Ari Sihvola, Pasi Yla-Oijala, Kevin Conley, and fahime Seyedheydari
DOI: 10.1364/JOSAB.456468 Received 17 Feb 2022; Accepted 11 May 2022; Posted 17 May 2022 View: PDF
Abstract: We investigate the electromagnetic response of anisotropic copper antimony disulfide (CuSbS₂) nanoparticles and layers embedded with them for solar applications and near-infrared (NIR) sensors using computational methods. To this end we calculate the scattering and absorption efficiencies of oblate spheroidal CuSbS₂ nanoparticles using the surface integral equation method. We further investigate the optical response of thin layers containing CuSbS₂ spheroids at low volume fraction using a Monte Carlo method. We find that response of these layers can be considerably modified by changing the short axis length and the orientation of the particles within the layer with respect to the incoming radiation. This allows engineering the layers for specific polarization-dependent-response applications.
Effects of substrate on cavity plasmon polaritons in monolayer MoS₂ embedded in an asymmetric cavity
Taiyang Guo, Lei Hou, Wen Xu, Yiming Xiao, and Lan Ding
DOI: 10.1364/JOSAB.459412 Received 24 Mar 2022; Accepted 11 May 2022; Posted 17 May 2022 View: PDF
Abstract: The coupling between plasmons in two-dimensional materials and photons can be enhanced by a Fabry-Pérot (FP) cavity, leading to the formation of cavity plasmon polaritons (CPPs). In this work, we theoretically investigate the effects of substrate on CPPs in monolayer (ML) molybdenum disulfide (MoS₂) embedded in an asymmetric FP cavity. The optical conductivity of ML MoS₂ used here is described by the Drude-Smith model, in which the substrate-induced electronic localization effect is considered. This effect has been experimentally demonstrated for CVD grown MoS₂ in our recent work. Herein, the investigation shows the existence of three types of CPPs in this asymmetric plasmonic system. Meanwhile, we also demonstrate that the substrate can affect the properties of these modes through different mechanisms. These results not only can give us insight into the effects of substrate on plasmon polaritons, but also remind us that the differences between the realistic optical parameters of MoS₂ and the ideal ones cannot be neglected in many situations. Moreover, we hope this study can push forward the design and optimization of plasmonic devices based on MoS₂, such as sensors, attenuators, and detectors.
Implementation of empirical modified generalized Harvey-Shack scatter model in smooth surface
Zhanpeng Ma, hu wang, and Qinfang Chen
DOI: 10.1364/JOSAB.455182 Received 02 Feb 2022; Accepted 11 May 2022; Posted 11 May 2022 View: PDF
Abstract: We proposed a modified generalized Harvey-Shack model by adding the empirical correction factor related to the scattering angle on the basis of the original theory. The result shows that the modified model reduces the root mean square error (RMSE) from less than 2% to less than 1%, and the relative peak error from less than 50% to less than 20%, which significantly improves the accuracy of scattering prediction. The prediction of Rayleigh-Rice model is not as good as the Harvey-Shack model. The RMSE of Rayleigh-Rice model is within 2.5% and the relative peak error is within 60%.
Theoretical Study of Borate Nonlinear Optical Crystals in low Symmetry
DOI: 10.1364/JOSAB.459844 Received 30 Mar 2022; Accepted 11 May 2022; Posted 11 May 2022 View: PDF
Abstract: Borate nonlinear optical (NLO) crystals are widely applied in generating important spectrum of coherent light that usual laser sources cannot cover. Besides the well-known examples of -BaB2O4 (BBO), LiB3O5 (LBO) and KBe2BO3F2 (KBBF) in uniaxial or orthorhombic symmetry, there are some recent developed borates in monoclinic or even lower symmetries, such as. BiB3O6 (BIBO), La2CaB10O19 (LCB), YCa4O(BO3)3 (YCOB) and Ca5(BO3)3F (CBOF). For those low symmetry NLO crystals, it is challenging to fully characterize their optical properties experimentally. Theoretical calculation can simultaneously give the linear optical and NLO properties with the help of high precise method recently developed. However, till now there seems lack of theoretical study that shows fundamentally agreement with the observed values for those properties interested. In this study, using the CRYSTAL17 code, an ab initio program based on a linear combination of atomic orbitals approach together with coupled perturbed Kahn-Sham approximation for first and second order susceptibilities, properties of dielectric constant ϵ_ij and second order susceptibility χ_ijk^((2)) (or SHG coefficients d_ijk^2ω) matrices of the above low symmetry crystals were obtained. From the calculated dielectric ϵ_ij tensor, the correct principal dielectric axes could be obtained through Euler rotations and they usually agree with experiments within several degrees. The same rotation transforms the calculated SHG coefficients into the dielectric frame and excellent agreement are found for YCOB and LCB (a confusion of sign difference can be solved). For BIBO, it is found special care must be taken due to the lone pair or softness of the Bi3+ ion in the structure. Using measured refractive indices, the effective NLO coefficients deff and optimum phase matching conditions for harmonic generations can be predicted, especially for CBOF which is still not fully characterized. This study shows that the calculation can reproduce the measured propertied in high precision and can confirm or solve disputes of different experiments for both of the values and signs and hopefully the theoretical approach can play more important role to advance the developments and applications of the low symmetry NLO materials.
Modulation instability generation with blue-detuned pump laser in coupled microcavities
Zihao Cheng, Dongmei HUANG, Feng Li, Chao Lu, and Ping Kong Wai
DOI: 10.1364/JOSAB.452366 Received 03 Jan 2022; Accepted 09 May 2022; Posted 10 May 2022 View: PDF
Abstract: Optical frequency combs based on microcavities with Kerr nonlinearity are promising frequency comb sources for many commercial applications. A typical Kerr soliton comb is generated in a nonlinear microcavity with anomalous dispersion pumped by a red-detuned continuous-wave laser. The compact structure of microcavities makes them sensitive to thermal fluctuation and the red-detuned pumping regime is thermally unstable. Modulation instability (MI) is the basis for Kerr soliton comb generation. In a microcavity with nearly zero dispersion, the first pair of MI modes can only grow with red-detuned pump laser. In this paper, we find that MI generation is possible with blue-detuned pump lasers for coupled microcavities with nearly zero dispersion. We study a microcavity with Kerr nonlinearity coupled with an auxiliary microcavity with negligible nonlinearity. By theoretical analysis, we find that the coupled microcavities can create a region supporting MI generation in the blue-detuned side of the nonlinear cavity’s resonance, whereas there is no blue-detuned MI generation in a single nonlinear microcavity. The properties of the blue-detuned MI region are determined by the coupling coefficient between the two microcavities, the loss of the auxiliary cavity and the detuning between the modes of the two microcavities. The size and location of the blue-detuned MI region can be varied by tuning these parameters. Numerical simulations of MI generation based on the blue-detuned MI region in microcavities are presented. As a natural extension, by considering more modes, MI comb generations with both anomalous and normal dispersion are also numerically simulated.
Temporal quality of post-compressed pulses at large compression factors
Esmerando Escoto, Anne-Lise Viotti, Skirmantas Alisauskas, Henrik Tuennermann, Ingmar Hartl, and Christoph Heyl
DOI: 10.1364/JOSAB.453901 Received 18 Jan 2022; Accepted 08 May 2022; Posted 10 May 2022 View: PDF
Abstract: Post-compression of ultra-short laser pulses via self-phase modulation is routinely employed for the generation of laser pulses with optical bandwidths reaching far beyond the laser gain limitations. While high compression factors can be routinely achieved, the compressed pulses typically suffer from temporal quality degradation. We numerically and experimentally analyze the deterioration of different measures of temporal quality with increasing compression factor and show how appropriate dispersion management and cascading of the post-compression process can be employed to limit the impact of this effect. The demonstrated saturation of pulse quality degradation at large compression factors puts novel femtosecond laser architectures based on post-compressed pico- or even nanosecond laser systems in sight.
Chirality sorting using structured caustic vector vortex field
DOI: 10.1364/JOSAB.462509 Received 27 Apr 2022; Accepted 08 May 2022; Posted 10 May 2022 View: PDF
Abstract: In this work, we theoretically demonstrate that the simultaneous manipulation of both the orbital angular momentum and the polarization conversion can be realized in a structured caustic vector vortex field. Under a slight focusing condition, the structured caustic vector vortex field would be auto focused into dual foci with specific topological charge and orthogonal polarizations, which can be manipulated through adjusting the initial state of polarization distribution and a caustic phase applied on the illumination. Furthermore, we demonstrate that the structured focal field carrying opposite spin angular momentum is suitable to sort chiral nanoparticles, in which the different energy flow directions would bring distinct dynamic behaviors to enantiomers. This finding may have potential applications in all-optical enantiopure chemical syntheses and enantiomer separations in pharmaceuticals.
Thermally reconfigurable extraordinary terahertz transmission using vanadium dioxide
Seyed Hadi Badri, Hadi Soofi, and Sanam Nahaie
DOI: 10.1364/JOSAB.459639 Received 28 Mar 2022; Accepted 07 May 2022; Posted 09 May 2022 View: PDF
Abstract: We numerically demonstrate a reconfigurable extraordinary terahertz transmission based on a phase-change material of vanadium dioxide (VO2). The proposed hybrid metasurface is composed of an array of subwavelength apertures perforated on a gold film. The holes are partially filled with annular VO2 and gold disks to control the effective aperture area and the modes inside the aperture. Switching between the insulator and the metallic phase of VO2 provides a convenient way to shift the transmission window. We present two designs offering redshift or blueshift of the extraordinary terahertz transmission. Upon phase transition from the insulator to the metallic phase, in the first design, the transmission peak redshifts from 0.82 to 1.02 THz while in the second design the transmission peak blueshifts from 0.71 to 0.77 THz. Furthermore, the transmission level and resonance frequency can be modulated by controlling the partial phase transition of the VO2. The potential applications for the proposed structures are terahertz modulators and reconfigurable filters.
Guided Mode Resonance Sensors: Different Schemes for Different Applications
Morteza Maleki and Mahdiyeh Mehran
DOI: 10.1364/JOSAB.449373 Received 23 Nov 2021; Accepted 06 May 2022; Posted 09 May 2022 View: PDF
Abstract: This work performs a quantitative comparison between different dielectric-based guided-mode resonance (D-GMR) sensors. To this end, diverse D-GMR structures are classified into three different classes, and their sensitivity (S) is compared with each other. For one of these classes in various schemes, sensitivity is investigated for the transverse electric and magnetic (TE and TM) modes. Moreover, grating height effects are studied for different cases in this category, where analytical sensitivity equations are used as the benchmarks. Then, the three classes are compared and based on the numerical results besides analytical equations, various applications are proposed for different structures in the refractive index (RI) of interest. Comparing our results with the recent works, we prove that the proposed classification leads to great sensing performances and the predictions are reliable. Comparison has been performed for methane as a gas sample (with RI of 1.0003) and hemoglobin solution and toluene as two different analytes (with RIs of 1.33 and 1.4778, respectively). Obtained results show the sensitivity of S = 1427.3 nm/RIU for methane with a detection precision of one to few volume percentages in the air (can also be calibrated to illuminate the fabrication variation errors). For hemoglobin sensitivity of 1073.4 nm/RIU is obtained (with limit-of-detection of 116.15 mg/lit for 65 g/lit of hemoglobin in water) while for toluene sensor S = 1019.7 nm/RIU is calculated. As a general result, high FoM/sensitivity can be achieved for a wide range of applications, from gases to high RI analytes, using our proposed classifications.
Simulation, optimization and characterization of AR surfaces for use with unique high-throughput fabrication techniques
Alexander Winters, Mark Mirotznik, Stephen Furst, Nichole Cates, and Lauren Micklow
DOI: 10.1364/JOSAB.455424 Received 02 Feb 2022; Accepted 04 May 2022; Posted 04 May 2022 View: PDF
Abstract: Optical anti-reflective (AR) surfaces are capable of improving performance of solar cells, HUD displays, and other important optical applications. However, fabricating these surfaces in a cost-effective way for large-area product applications has continued to be a challenge. In this paper we use Rigorous Coupled Wave (RCW) simulation to determine the effects fabrication constraints have on the performance of a sub-wavelength, anti-reflective pattern created with a new, highly scalable process. The goal is to use simulation results to drive meaningful improvements to the fabrication process, thereby broadening the applicability of AR surfaces. A number of possible AR surface geometries are simulated and analyzed, emphasizing the optimal geometries for low aspect ratios. The main parameters that dictate the efficiency and fabricability of AR surfaces are reviewed. Finally, we experimentally characterize a sample AR surface to validate the model and find the benefits and limitations of the new scalable fabrication process. RCW simulation indicates that parabolic and sinusoidal AR surface models obtain the best reflectance results, with the sinusoidal model performing better at low aspect ratios. Further analysis demonstrates that AR surfaces with higher fill-factors and higher aspect ratios show noticeably lower reflectance. Experimental validation of a sample AR surface showed good conformity to simulation results, opening the door for further development of novel fabrication processes.
Dispersion properties of a slab waveguide with a graded-index core layer and a nonlinear cladding using the WKB approximation method
Abdulkarem Almawgani, Sofyan Taya, Aya Hussein, and Ilhami Colak
DOI: 10.1364/JOSAB.458569 Received 15 Mar 2022; Accepted 03 May 2022; Posted 05 May 2022 View: PDF
Abstract: Graded-index waveguides deserve investigation because they are more practical than those of step-index profiles. In this communication, a three-layer slab waveguide in which the core film has an exponentially graded refractive index is assumed. In this case, the film and substrate layers merge smoothly to form one layer of refractive index n(x) which is equal to nf at the cladding-film boundary and ns deep in the substrate layer. The cladding layer is made of a Kerr-type nonlinear material. An exact solution of such a waveguide structure is not possible. Approximation techniques are usually used in these cases. We employ the WKB approximation method to find an approximate dispersion relation of the proposed waveguide in terms of the asymmetry parameters a, b and V. The universal dispersion curves are studied in detail. A number of interesting features are observed, such as the lack of a cutoff thickness related to the symmetric waveguide structure of a = 0. The b-values are all less than one which corresponds to guided modes.
Multiple-Frequency-Spaced and -Offset Flat Optical Comb Generation UsingMultiple-Parallel Phase Modulator: Theory and Design
Takahide Sakamoto and Akito Chiba
DOI: 10.1364/JOSAB.455652 Received 09 Feb 2022; Accepted 03 May 2022; Posted 03 May 2022 View: PDF
Abstract: We propose and investigate reconfigurable multiple-frequency (MF)-spaced, -offset flat optical comb generation using an electro-optic (EO) multiple-parallel phase modulator (MP-PM). In the technique, the frequency spacing and offset of the generated comb can be flexibly controlled through the EO modulation process without relying on any optical filters, which are configurable at frequencies much beyond the EO modulation bandwidth, e.g., 50, 100 GHz, or higher.In this paper, the driving conditions of the MP-PM for the MF-spaced and MF-offset comb generation with great spectral flatness are analytically clarified and summarized as simple formulas. Re-partitioning of the modulator arms is also discussed for flexible comb generation with higher conversion efficiency.
Scattering evaluation of an infinite PEC plane coated with the anisotropic medium under arbitrary source excitation based on Dyadic Green's Functions
Siyuan He, Jingjing He, Guoqiang Zhu, Wancong Li, Mengbo Hua, and Chao Li
DOI: 10.1364/JOSAB.448114 Received 08 Nov 2021; Accepted 29 Mar 2022; Posted 30 Mar 2022 View: PDF
Abstract: A spectral-domain asymptotic method based on the dyadic Green’s function is proposed to study the EM scattering of an infinite PEC plane coated with the uniaxial electric anisotropic medium(UEAM) under arbitrary source excitation. We specifically analyze the ray propagation path of incidence wave from the individual point source, which acts at the planar-layered medium structure to obtain the dyadic Green’s functions (DGFs) of different types of EM waves. These DGFs from the reflected, transmitted and entire secondary scattered fields are employed to establish the relationship between the arbitrary excitation source and different types of scattered fields. According to the corresponding “source-field” connection between the excitation source and the scattered field components in the spectral domain, we can first derive the expression of the spectral-domain DGF matrix components and then utilize the saddle point method to obtain the spatial-domain dyadic Green's function. Finally, we construct the scattered field for an infinite PEC plane coated with the UEAM layer under arbitrary source excitation through the integral equation solution. The comparison of simulation results from the proposed method and the MoM method confirms the algorithm validation. So it is expected to be a valid algorithm for dealing with electrically large and complex targets coated with the UEAM layer under any source excitation in the future.