Contents 2 Issue (s), 28 Article (s)

Vol. 13, Iss.6—Jun.1, 2025 • pp: 1438-1496 Spec. pp:

Vol. 13, Iss.5—May.1, 2025 • pp: 1106-1437 Spec. pp:

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Research ArticlesVol. 13, Iss.6-Jun..1,2025
Fiber Optics and Optical Communications
Concept and experimental demonstration of physics-guided end-to-end learning for optical communication systems
Qiarong Xiao, Chen Ding, Tengji Xu, Chester Shu, and Chaoran Huang
Driven by advancements in artificial intelligence, end-to-end learning has become a key method for system optimization in various fields, including communications. However, applying learning algorithms such as backpropagation directly to communication systems is challenging due to their non-differentiable nature. Existing methods typically require developing a precise differentiable digital model of the physical system, which is computationally complex and can cause significant performance loss after deployment. In response, we propose a novel end-to-end learning framework called physics-guided learning. This approach performs the forward pass through the actual transmission channel while simplifying the channel model for the backward pass to a simple white-box model. Despite the simplicity, both experimental and simulation results show that our method significantly outperforms other learning approaches for digital pre-distortion applications in coherent optical fiber systems. It enhances training speed and accuracy, reducing the number of training iterations by more than 80%. It improves transmission quality and noise resilience and offers superior generalization to varying transmission link conditions such as link losses, modulation formats, and scenarios with different transmission distances and optical amplification. Furthermore, our new end-to-end learning framework shows promise for broader applications in optimizing future communication systems, paving the way for more flexible and intelligent network designs.
Photonics Research
  • Publication Date: May. 16, 2025
  • Vol. 13, Issue 6, 1469 (2025)
Imaging Systems, Microscopy, and Displays
Upsampled PSF enables high accuracy 3D superresolution imaging with sparse sampling rate
Jianwei Chen, Wei Shi, Jianzheng Feng, Jianlin Wang..., Sheng Liu and Yiming Li|Show fewer author(s)
Photonics Research
  • Publication Date: May. 16, 2025
  • Vol. 13, Issue 6, 1485 (2025)
Optoelectronics
Electron–phonon coupling enhanced by graphene/PZT heterostructure for infrared emission and optical information transmission
Kaixi Bi, Linyu Mei, Shuqi Han, Jialiang Chen..., Yan Zhuang, Exian Liu, Wenhui Wang and Xiujian Chou|Show fewer author(s)
High-performance infrared emitters hold substantial importance in modern engineering and physics. Here, we introduce graphene/PZT (lead zirconate titanate) heterostructure as a new platform for the development of infrared source structure based on an electron–phonon coupling and emitting mechanism. A series of electrical characterizations including carrier mobility [11,361.55 cm2/(V·s)], pulse current (30 ms response time), and cycling stability (2000 cycles) modulated by polarized film was provided. Its maximum working temperature reaches 1041 K (768°C), and it was broken at 1173 K (900°C) within 1.2 s rise time and fall time. Based on Wien’s displacement law, the high temperature will lead to near–mid–far thermal infrared when the heterostructure is applied to external voltages, and obvious bright white light could be observed by the naked eye. The changing process has also been recorded by mobile phone. In subsequent infrared emitting applications, 11 V bias voltage was applied on the PZT/graphene structure to produce the temperature change of 299 to 445 K within 0.96 s rise time and 0.98 s fall time. To demonstrate its optical information transmission ability, we exhibited “N, U, C” letters by the time-frequency method at 3 mm×3 mm@20 m condition. Combining with spatial Morse code infrared units, alphabetic information could also be transmitted by infrared array images. Compared with the traditional infrared emitter, the electron–phonon enhancing mechanism and high-performance emission properties of the heterostructure demonstrated a novel and reliable platform for further infrared optical applications.
Photonics Research
  • Publication Date: May. 16, 2025
  • Vol. 13, Issue 6, 1459 (2025)
Surface Optics and Plasmonics
Solar-blind ultraviolet imaging with a diamond metalens
Wen-Jie Dou, Xun Yang, Cheng-Long Zheng, Hua-Ping Zang..., Pei-Nan Ni, Yi-Yang Xie, Pei-Pei Chen and Chong-Xin Shan|Show fewer author(s)
Imaging in the solar blind ultraviolet (UV) region offers significant advantages, including minimal interference from sunlight, reduced background noise, low false-alarm rate, and high sensitivity, and thus has important applications in early warning or detection of fire, ozone depletion, dynamite explosions, missile launches, electric leakage, etc. However, traditional imaging systems in this spectrum are often hindered by the bulkiness and complexity of conventional optics, resulting in heavy and cumbersome setups. The advent of metasurfaces, which use a two-dimensional array of nano-antennas to manipulate light properties, provides a powerful solution for developing miniaturized and compact optical systems. In this study, diamond metalenses were designed and fabricated to enable ultracompact solar-blind UV imaging. To prove this concept, two representative functionalities, bright-field imaging and spiral phase contrast imaging, were demonstrated as examples. Leveraging diamond’s exceptional properties, such as its wide bandgap, high refractive index, remarkable chemical inertness, and high damage threshold, this work not only presents a simple and feasible approach to realize solar-blind imaging in an ultracompact form but also highlights diamond as a highly capable material for developing miniaturized, lightweight, and robust imaging systems.
Photonics Research
  • Publication Date: May. 16, 2025
  • Vol. 13, Issue 6, 1452 (2025)
Research ArticlesVol. 13, Iss.5-May..1,2025
Holography, Gratings, and Diffraction
Intelligent tailoring of a broadband orbital angular momentum comb towards efficient optical convolution | Editors' Pick
Shiyun Zhou, Lang Li, Yishu Wang, Liliang Gao..., Zhichao Zhang, Chunqing Gao and Shiyao Fu|Show fewer author(s)
Due to the high-dimensional characteristics of photon orbital angular momentum (OAM), a beam can carry multiple OAMs simultaneously thus forming an OAM comb, which has been proved to show significant potential in both classical and quantum photonics. Tailoring broadband OAM combs on demand in a fast and accurate manner is a crucial basis for their application in advanced scenarios. However, obtaining phase-only gratings for the generation of arbitrary desired OAM combs still poses challenges. In this paper, we propose a multi-scale fusion learning U-shaped neural network that encodes a phase-only hologram for tailoring broadband OAM combs on-demand. Proof-of-principle experiments demonstrate that our scheme achieves fast computational speed, high modulation precision, and high manipulation dimensionality, with a mode range of -75 to +75, an average root mean square error of 0.0037, and a fidelity of 85.01%, all achieved in about 30 ms. Furthermore, we utilize the tailored broadband OAM combs in conducting optical convolution calculation, enabling vector convolution for arbitrary discrete functions, showcasing the extended capability of our proposal. This work opens, to our knowledge, new insight for on-demand tailoring of broadband OAM combs, paving the way for further advancements in high-dimensional OAM-based applications.
Photonics Research
  • Publication Date: Apr. 21, 2025
  • Vol. 13, Issue 5, 1148 (2025)
Holography, Gratings, and Diffraction
Holographic multi-waveguide system: towards implementation in wearable sensor technologies
Pamela Stoeva, Tatsiana Mikulchyk, Suzanne Martin, Maria Antonietta Ferrara..., Giuseppe Coppola and Izabela Naydenova|Show fewer author(s)
Holographic optical elements (HOEs) are integral to advancements in optical sensing, augmented reality, solar energy harvesting, biomedical diagnostics, and many other fields, offering precise and versatile light manipulation capabilities. This study, to the best of the authors’ knowledge, is the first to design and fabricate an HOE mutli-waveguide system using a thermally and environmentally stable photopolymerizable hybrid sol-gel (PHSG) for sensing applications. Using a 476.5 nm recording wavelength, 60% diffraction efficiency PHSG holographic waveguides of spatial frequency of 1720 lines/mm were successfully fabricated to function as in- and out-couplers at 632.8 nm and 700 nm wavelength, respectively. The waveguides were integrated into a polydimethylsiloxane (PDMS) microfluidic system, guiding excitation light of 632.8 nm wavelength into and extracting fluorescence light signal peaking at 700 nm from a location filled with methylene blue water solution. Further, to demonstrate the potential of the proposed optical system, four holographic waveguides were recorded by peristrophic and angular multiplexing in the same location of the material and the input beam was delivered into four spatially separated channels by total internal reflection in the sol-gel layer, thus, successfully highlighting the capabilities and advantages of HOE waveguides for parallel interrogation of multiple locations in a wearable sensor. This study demonstrates the efficiency and versatility of PHSG-based HOE waveguides, underscoring their potential to enhance photonic device design and performance across various optical applications.
Photonics Research
  • Publication Date: May. 01, 2025
  • Vol. 13, Issue 5, 1428 (2025)
Instrumentation and Measurements
Ultrafast ranging using a dispersion-controlled dual-swept laser
Wei Du, Lei Chen, Yujia Li, Jindong Wang..., Yulong Cao, Ligang Huang, Leilei Shi, Lei Gao, Lei Wei and Tao Zhu|Show fewer author(s)
Ranging is indispensable in a variety of fields, encompassing basic science, manufacturing, production, and daily life. Although traditional methods based on the dispersive interferometry (DPI) in the frequency domain provide high precision, their measurement speed is slow, preventing the capture and measurement of dynamic displacements. Here, we propose a fast and precise ranging method based on the dispersion-controlled dual-swept laser (DCDSL), which allows the dynamical displacement measurement of the target under test. Due to the slight frequency sweeping speed difference between the signal and reference lights, there is a zero-frequency point of the oscillation (ZPO) generated in the interference signal, whose position in the time domain is linearly related to the relative delay between the signal and reference lights. Utilizing phase demodulation of the interference signal from the DCDSL and the fitting algorithm, the time-domain position of ZPO is accurately found, which precisely maps to the displacement of the target in real time without direction ambiguity. The fast frequency sweeping rate ensures fast ranging with the MHz order refresh frame. We have experimentally demonstrated its capabilities for precise measurement of static distances and the capture of dynamic displacement processes through simulations and experiments, with the measurement range encompassing the entire interference period (56 mm). Compared to a calibrated motorized displacement platform, the residual error for full-range distance measurements is within 10 μm, and the error in average speed during dynamic processes is 0.46%. Additionally, the system exhibits excellent stability, achieving a minimum Allan deviation of 4.25 nm over an average duration of approximately 4 ms. This method ensures high precision while maintaining a simple system, thereby advancing the practical implementation of ultrafast length metrology.
Photonics Research
  • Publication Date: Apr. 21, 2025
  • Vol. 13, Issue 5, 1182 (2025)
Instrumentation and Measurements
Single-shot optical transfer delay measurement with sub-picosecond accuracy and sub-millisecond range
Lihan Wang, Xiangchuan Wang, Xi Liu, Yue Yang..., Shupeng Li, Sihao Yang, Qianwen Sang, Zhijian Zhang, Jingxian Wang and Shilong Pan|Show fewer author(s)
Optical transfer delay (OTD) is essential for distributed coherent systems, optically controlled phased arrays, fiber sensing systems, and quantum communication systems. However, existing OTD measurement techniques typically involve trade-offs among accuracy, range, and speed, limiting the application in the fields. Herein, we propose a single-shot OTD measurement approach that simultaneously achieves high-accuracy, long-range, and high-speed measurement. A microwave photonic phase-derived ranging with a nonlinear interval microwave frequency comb (MFC) and a discrete frequency sampling technique is proposed to conserve both frequency and time resources, ensuring high-accuracy and ambiguity-free measurements. In the proof-of-concept experiment, a delay measurement uncertainty at the 10-9 level with a single 10 μs sampling time is first reported, to our knowledge. The method is also applied to coherently combine two distributed signals at 31.8 GHz, separated by a 2 km optical fiber. A minimal gain loss of less than 0.0038 dB compared to the theoretical value was achieved, corresponding to an OTD synchronization accuracy of 0.3 ps.
Photonics Research
  • Publication Date: Apr. 30, 2025
  • Vol. 13, Issue 5, 1302 (2025)
Integrated Optics
Experimental evaluation of continuous and pixelated dispersive optical phased arrays for 2D beam steering
Mennatallah Kandil, Mathias Prost, Jon Kjellman, Wim Bogaerts, and Marcus Dahlem
Dispersive optical phased arrays (DOPAs) offer a method for fast 2D beam scanning for solid-state LiDAR with a pure passive operation, and therefore low control complexity and low power consumption. However, in terms of scalability, state-of-the-art DOPAs do not easily achieve a balanced performance over the specifications of long-range LiDAR, including the number of pixels (resolvable points) and beam quality. Here, we experimentally demonstrate the pixelated DOPA concept, which overcomes the scaling challenges of classical (continuous) DOPAs by introducing a new design degree of freedom: the discretization of the optical delay lines distribution network into blocks. We also present the first demonstration of the unbalanced splitter tree architecture for the DOPA distribution network, incorporated in both the continuous DOPA and the pixelated DOPA variations. The small-scale demonstration circuits can scan over a field of view of 15°×7.2°, where the continuous DOPA provides 16×25 pixels, while the pixelated DOPA provides 4×25 pixels, for a 1500 to 1600 nm wavelength sweep. The pixelated DOPA exhibits a side lobe suppression ratio with a median of 7.6 dB, which is higher than that of the continuous version, with a median of 3.6 dB. In addition, the ratio of the main beam to the background radiation pattern is 11 dB (median value) for the pixelated DOPA, while for the continuous DOPA, it is 9.5 dB. This is an indication of a higher beam quality and lower phase errors in the pixelated DOPA. The degree of discretization, combined with other design parameters, will potentially enable better control over the beam quality, while setting practical values for the number of pixels for large-scale DOPAs.
Photonics Research
  • Publication Date: Apr. 30, 2025
  • Vol. 13, Issue 5, 1330 (2025)
Integrated Optics
Lithium tantalate microring cavities with a Q factor exceeding 10 million | Spotlight on Optics
Jianfeng He, Xinyi Zhao, Jian-Bin Xu, and Xiankai Sun
Thin-film lithium niobate has attracted great interest in high-speed communication due to its unique piezoelectric and nonlinear properties. However, its high photorefraction and slow electro-optic response relaxation introduce the possibility of transmission bit errors. Recently, lithium tantalate, another piezoelectric and nonlinear material, has emerged as a promising candidate for active photonic integrated devices because of its weaker photorefraction, faster electro-optic response relaxation, higher optical damage threshold, wider transparency window, and lower birefringence compared with lithium niobate. Here, we developed an ultralow-loss lithium tantalate integrated photonic platform, including waveguides, grating couplers, and microring cavities. The measured highest optical Q factor of the microring cavities is beyond 107, corresponding to the lowest waveguide propagation loss of 1.88 dB/m. The photorefractive effect in such lithium tantalate microring cavities was experimentally demonstrated to be 500 times weaker than that in lithium niobate microcavities. This work lays the foundation for a lithium tantalate integrated platform for achieving a series of on-chip optically functional devices, such as periodically poled waveguides, acousto-optic modulators, and electro-optic modulators.
Photonics Research
  • Publication Date: May. 01, 2025
  • Vol. 13, Issue 5, 1385 (2025)
Integrated Optics
Integrated spatial photonic XY Ising sampler based on a high-uniformity 1 × 8 multi-mode interferometer
Xin Ye, Wenjia Zhang, and Zuyuan He
Spatial photonic Ising machines, as emerging artificial intelligence hardware solutions by leveraging unique physical phenomena, have shown promising results in solving large-scale combinatorial problems. However, spatial light modulator enabled Ising machines still remain bulky, are very power demanding, and have poor stability. In this study, we propose an integrated XY Ising sampler based on a highly uniform multimode interferometer and a phase shifter array, enabling the minimization of both discrete and continuous spin Hamiltonians. We elucidate the performance of this computing platform in achieving fully programmable spin couplings and external magnetic fields. Additionally, we successfully demonstrate the weighted full-rank Ising model with a linear dependence of 0.82 and weighted MaxCut problem solving with the proposed sampler. Our results illustrate that the developed structure has significant potential for larger-scale, reduced power consumption and increased operational speed, positioning it as a versatile platform for commercially viable high-performance samplers of combinatorial optimization problems.
Photonics Research
  • Publication Date: May. 01, 2025
  • Vol. 13, Issue 5, 1419 (2025)
Lasers and Laser Optics
Unveiling intracavity soliton evolution dynamics of a mode-locked fiber laser along the dispersion map
Jiarun Zhang, Tianchang Lu, Xiankun Yao, Yusheng Zhang..., Dong Mao, Chao Zeng, Xiang Hao, Longhua Tang, Yudong Cui, Cuifang Kuang and Xu Liu|Show fewer author(s)
Mode-locked fiber lasers are excellent platforms for soliton generation. Solitons exhibit distinct distribution and evolution characteristics depending on the net dispersion of the laser cavity. Here we propose an experimental scheme to reconstruct the intracavity dynamics of solitons within a mode-locked fiber laser. The proposed scheme is facilitated by disposing multiple output ports at different positions throughout the cavity, thereby enabling in-depth observation and manipulation of soliton evolution along the dispersion map. The experimental results verify corresponding simulations and explain some phenomena from the perspective of soliton evolution. Our results offer a pathway for comprehensive analyses of intracavity pulse dynamics, fostering advancements in nonlinear and ultrafast optics.
Photonics Research
  • Publication Date: Apr. 21, 2025
  • Vol. 13, Issue 5, 1130 (2025)
Lasers and Laser Optics
All-fiber-structure high-power mid-infrared gas-filled hollow-core-fiber amplified spontaneous emission source
Weihua Song, Yu Wen, Qian Zhang, Xin Zhang, and Pu Wang
Hollow-core-fiber (HCF) gas lasers (GLs) have garnered significant interest as a novel approach for generating mid-infrared lasers, owing to their inherent benefits of rich emission wavelength, high beam quality, and high output power potential. However, they are mostly achieved by a free-space coupling structure, which has a major drawback of being prone to vibrations and other environmental variations. Here, we devise and implement an all-fiber-structure gas-filled HCF amplified spontaneous emission (ASE) source at 3.1 μm based on the reverse tapering and angle-cleaved fusion splicing techniques. By optimizing the C2H2 gas pressure, a maximum mid-infrared output power of 6.59 W was obtained, corresponding to a slope efficiency of 19.74% and near-diffraction-limited beam qualities of Mx2=1.03 and My2=1.06. Furthermore, with a similar all-fiber configuration, a CO2-filled HCF ASE source at 4.3 μm with output power exceeding 1.4 W was generated. To the best of our knowledge, the proposed all-fiber-structure HCF gas light source demonstrates the longest wavelength and highest power reported to date. The development of mid-infrared HCF gas light sources in an all-fiber configuration represents a significant step toward miniaturized HCF lasers, which hold promise as powerful new tools for application in laser medicine, space communication, and other scientific research.
Photonics Research
  • Publication Date: Apr. 21, 2025
  • Vol. 13, Issue 5, 1137 (2025)
Nanophotonics and Photonic Crystals
Floquet hybrid skin-topological effects in checkerboard lattices with large Chern numbers
Yi-Ling Zhang, Li-Wei Wang, Yang Liu, Zhao-Xian Chen, and Jian-Hua Jiang
Non-Hermitian topology provides an emergent research frontier for studying unconventional topological phenomena and developing new materials and applications. Here, we study the non-Hermitian Chern bands and the associated non-Hermitian skin effects in Floquet checkerboard lattices with synthetic gauge fluxes. Such lattices can be realized in a network of coupled resonator optical waveguides in two dimensions or in an array of evanescently coupled helical optical waveguides in three dimensions. Without invoking nonreciprocal couplings, the system exhibits versatile non-Hermitian topological phases that support various skin-topological effects. Remarkably, the non-Hermitian skin effect can be engineered by changing the symmetry, revealing rich non-Hermitian topological bulk-boundary correspondences. Our system offers excellent controllability and experimental feasibility, making it appealing for exploring diverse non-Hermitian topological phenomena in photonics.
Photonics Research
  • Publication Date: Apr. 30, 2025
  • Vol. 13, Issue 5, 1321 (2025)
Nanophotonics and Photonic Crystals
Dual-channel tunable multipolarization adapted terahertz spatiotemporal vortices generating device
Fangze Deng, Ke Ma, Yumeng Ma, Xiang Hou..., Zhihua Han, Yuchao Li, Keke Cheng, Yansheng Shao, Chenglong Wang, Meng Liu, Huiyun Zhang and Yuping Zhang|Show fewer author(s)
Spatiotemporal optical vortices (STOVs) exhibit characteristics of transverse orbital angular momentum (OAM) that is perpendicular to the direction of pulse propagation, indicating significant potential for diverse applications. In this study, we employ vanadium dioxide and photonic crystal plates to design tunable transreflective dual-channel terahertz (THz) spatiotemporal vortex generation devices that possess multipolarization adaptability. In the reflection channel, we achieve active tunability of the topological dark lines by utilizing circularly polarized light, based on the topological dark phenomenon, and observe variations in the number of singularities across the parameter space from different observational perspectives. In the transmission channel, we generate independent vortex singularities using linearly polarized light. This multifunctional terahertz device offers a novel approach for the generation and active tuning of spatiotemporal vortices.
Photonics Research
  • Publication Date: May. 01, 2025
  • Vol. 13, Issue 5, 1408 (2025)
Nonlinear Optics
Towards high-power and ultra-broadband mid-infrared supercontinuum generation using tapered multimode glass rods
Esteban Serrano, Damien Bailleul, Frédéric Désévédavy, Pierre Béjot..., Grégory Gadret, Pierre Mathey, Frédéric Smektala and Bertrand Kibler|Show fewer author(s)
Simultaneously increasing the spectral bandwidth and average output power of mid-infrared supercontinuum sources remains a major challenge for their practical application. We particularly address this issue for the long mid-infrared spectral region through experimental developments of short tapered rods made from selenide glass by means of supercontinuum generation in the femtosecond regime. Our simple post-processing of glass rods unlocks potentially higher-power and coherent fiber-based supercontinuum sources beyond the 10-μm waveband. By using a 5-cm-long tapered Ge-Se-Te rod pumped at 6 μm, a supercontinuum spanning from 2 to 15 μm (3–14 μm) with an average output power of 93 mW (170 mW) is obtained for 500-kHz (1-MHz) repetition rate. Additional experiments on other glass families (silica and tellurite) covering distinct spectral regions are also reported to develop and support our analyses. We demonstrate that ultra-broadband spectral broadenings over entire glass transmission windows can be achieved in few-cm-long segments of tapered rods by a fine adjustment of input modal excitation. Numerical simulations are used to confirm the main contribution of the fundamental mode in the ultrafast nonlinear dynamics, as well as the possible preservation of coherence features. Our study opens a new route, to our knowledge, towards the power scaling of high-repetition-rate fiber supercontinuum sources over the full molecular fingerprint region.
Photonics Research
  • Publication Date: Apr. 21, 2025
  • Vol. 13, Issue 5, 1106 (2025)
Optical and Photonic Materials
Advancing photonic device capabilities via femtosecond laser modification of LPCVD-SiN microring resonator characteristics
Jia Du, Weixiao Xu, Runwei Zhou, Xiao Chen..., Ting Li, Xiongping Bao, Hong Wang, Weibiao Chen and Libing Zhou|Show fewer author(s)
Femtosecond pulsed lasers offer significant advantages for micro-/nano-modifications in integrated photonics. Microring resonators (MRRs), which are essential components in photonic integrated circuits (PICs), are widely employed in various fields, including optical communication, sensing, and filtering. In this study, we investigate the modification mechanisms associated with femtosecond laser interactions with MRRs fabricated on a low-pressure chemical vapor deposition (LPCVD)-silicon nitride (SiN) photonic platform, with emphasis on the post-fabrication trimming of second-order microring filters and MRR-based four-channel wavelength-division multiplexing (WDM). We examine 10 MRRs located at different positions on a wafer and discovered resonance wavelength shifts exceeding 1 nm due to fabrication-induced variations. Interactions between femtosecond lasers and LPCVD-SiN films resulted in silicon nanoclusters, which significantly redshifted the resonance wavelength of the MRRs. Additionally, the extinction ratio of MRRs improved by over 11.8 dB within the conventional band after laser modification. This technique is employed to enhance the performance of second-order MRRs and the four-channel WDM configuration, thus providing critical experimental evidence for leveraging femtosecond lasers to optimize LPCVD-SiN PICs.
Photonics Research
  • Publication Date: Apr. 30, 2025
  • Vol. 13, Issue 5, 1313 (2025)
Optical Devices
QBIC-based terahertz metasurface used for the detection of chlorpyrifos in tea
Tianqing Zhou, Binggang Xiao, Yong Du, and Jianyuan Qin
Pesticide residues in tea are an important problem affecting the sustainable development of the tea industry; thus, pesticide detection is the key to ensuring the quality and safety of tea. Here, a terahertz metasurface structure based on the quasi-bound state in the continuum is proposed, which consists of two copper microrods arranged periodically. This design in the metasurface provides strong local enhancement near the surface of the microstructure, significantly improving the interaction of light with the analyte, resulting in increased sensitivity. The simulated and experimental results show that the metasurface structure can be used to detect the refractive index of trace analytes with a high sensitivity and successfully detect low concentrations of chlorpyrifos in tea. This study provides a new idea for the detection of pesticide residues in tea.
Photonics Research
  • Publication Date: Apr. 21, 2025
  • Vol. 13, Issue 5, 1158 (2025)
Optical Devices
Efficient inverse design for tailoring a terahertz metagrating
Jia Shi, Guanlong Wang, Shaona Wang, Wenjing Yu..., Ling Liang, Weiling Fu, Pingjuan Niu, Jianquan Yao and Xiang Yang|Show fewer author(s)
The fast and accurate design of terahertz devices for specific applications remains challenging, especially for tailoring metadevices, owing to the complex electromagnetic characteristics of these devices and their large structural parameter space. The unique functionalities achieved by metadevices come at the cost of structural complexity, resulting in a time-consuming parameter sweep for conventional metadevice design. Here, we propose a general solution to achieve efficient inverse design for a terahertz metagrating via machine learning. Metagratings with different structural parameters were selected as illustrations to verify the effectiveness of this method. As proof-of-principle examples, the metagratings predicted via the inverse design model are numerically calculated and experimentally demonstrated. Initially, the physical modeling of a metagrating is performed via the finite element method (FEM). A spectrum dataset obtained from FEM simulation is prepared for the training of machine learning models. Then, trained machine learning models, including the Elman neural network (Elman), support vector machine (SVM), and general regression neutral network (GRNN), are used to predict probable structural parameters. The results of these models are compared and analyzed comprehensively, which verifies the effectiveness of the inverse design method. Compared with conventional methods, the inverse design method is much faster and can encompass a high degree of freedom to generate metadevice structures, which can ensure that the spectra of generated structures resemble the desired ones and can provide accurate data support for metadevice modeling. Furthermore, a metagrating tailored by an inverse design is used as a biological sensor to distinguish different microorganisms. The proposed data-driven inverse design method realizes fast and accurate design of the metagrating, which is expected to have great potential in metadevice design and tailoring for specific applications.
Photonics Research
  • Publication Date: Apr. 21, 2025
  • Vol. 13, Issue 5, 1172 (2025)
Optical Devices
Dual-frequency-range modulator based on a planar nested multiscale metasurface
Jing Yuan, Guichuan Xu, Zhengang Lu, Xinmeng Zhuang..., Huanping Zhou, Heyan Wang, Lin Han and Jiubin Tan|Show fewer author(s)
Multi-spectral and multi-functional optical components play a crucial role in fields such as high-speed communications and optical sensing. However, the interaction between different spectra and matter varies significantly, making it challenging to simultaneously achieve dynamic multi-spectral modulation capabilities. We designed a modulator based on a planar nested multiscale metasurface, incorporating silicon (Si) and perovskite as control materials, to modulate both microwave and terahertz (THz) ranges. Modulation of microwave and THz waves is achieved through visible light and near-infrared light pumping, with modulation depths of 94.03% and 90.77%, respectively. The modulator employs a planar nested multiscale metasurface, utilizing the odd-order nonlinear polarization properties of perovskite in the THz range and the linear absorption properties of Si in the microwave range to realize dual-frequency-range modulation. This research offers innovative insights for designing multi-spectral components applicable in all-optical coding metasurfaces and intelligent light windows.
Photonics Research
  • Publication Date: May. 01, 2025
  • Vol. 13, Issue 5, 1390 (2025)
Optical Devices
High-efficiency mode group demultiplexing based on diffractive optical network
Zhibing Liu, Siqing Zeng, Shuixian Yang, Yuetong Shi..., Hongfei Chen, Yaoming Feng, Shecheng Gao, Jiajing Tu, Dawei Wang, Zhaojian Chen and Zhaohui Li|Show fewer author(s)
Space division multiplexing (SDM) can achieve higher communication transmission capacity by exploiting more spatial channels in a single optical fiber. For weakly coupled few-mode fiber, different mode groups (MGs) are highly isolated from each other, so the SDM system can be simplified by utilizing MG multiplexing and intensity modulation direct detection. A key issue to be addressed here is MG demultiplexing, which requires processing all the modes within a single MG in contrast to MG multiplexing. Benefiting from the great light manipulation freedom of the diffractive optical network (DON), we achieve efficient separation of the MGs and receive them with the multimode fiber (MMF) array. To fully exploit the mode field freedom of the MMF, a non-deterministic mode conversion strategy is proposed here to optimize the DON, which enables high-efficiency demultiplexing with a much smaller number of phase plates. As a validation, we design a 6-MG demultiplexer consisting of only five phase plates; each MG is constituted by several orbital angular momentum modes. The designed average loss and crosstalk at the wavelength of 1550 nm are 0.5 dB and -25 dB, respectively. In the experiment, the loss after coupling to the MMF ranged from 4.1 to 4.9 dB, with an average of 4.5 dB. The inter-MG crosstalk is better than -12 dB, with an average of -18 dB. These results well support the proposed scheme and will provide a practical solution to the MG demultiplexing problem in a short-distance SDM system.
Photonics Research
  • Publication Date: May. 01, 2025
  • Vol. 13, Issue 5, 1400 (2025)
Optoelectronics
High-precision quasi-static sensing method based on WGM resonator self-modulation
Tao Jia, Enbo Xing, Jianglong Li, Jiamin Rong..., Hongbo Yue, Yujie Zhang, Guohui Xing, Yanru Zhou, Wenyao Liu, Jun Tang and Jun Liu|Show fewer author(s)
Whispering gallery mode (WGM) resonators have been widely researched for their high-sensitivity sensing capability, but there is currently a lack of high-sensitivity real-time sensing methods for quasi-static measurement. In this paper, within the framework of dissipative coupling sensing, a new method for quasi-static sensing based on the self-modulation of lithium niobate (LiNbO3) resonators is proposed. The LiNbO3 resonator actively modulates the signal to be measured, solving the challenge of real-time demodulation of quasi-static signals. The noise background is upconverted to a high frequency region with lower noise, further enhancing the detection limit. In the demonstration of quasi-static displacement sensing, a customized LiNbO3 resonator with a Q-factor of 2.09×107 serves as the high frequency modulation and sensing element, while the movable resonator acts as the displacement loading unit. Experimental and theoretical results show that the sensing response can be improved to 0.0416 V/nm by dissipation engineering to enhance the resonator evanescent field decay rate and orthogonal polarization optimization. The Allan deviation σ demonstrates a bias instability of 0.205 nm, which represents the best result known to date for microresonator displacement sensing in the quasi-static range. Our proposed scheme demonstrates competitiveness in high-precision quasi-static sensing and provides solutions for the high-precision real-time detection of low frequency or very low frequency acceleration, pressure, nanoparticles, or viruses.
Photonics Research
  • Publication Date: May. 01, 2025
  • Vol. 13, Issue 5, 1375 (2025)
Physical Optics
Symmetric and asymmetric Hall effect-like splitting of optical Stokes skyrmions via a hybrid multi-zone filter
Tian Xia, Jia Ma, Zhenwei Xie, and Xiaocong Yuan
In recent years, optical skyrmions have garnered increasing attention for their ability to introduce new degrees of freedom in manipulating optical fields. While most research has focused on creating innovative optical topological states such as merons and hopfions, there has been limited exploration into their manipulation, which hinders practical applications in this field. In this study, we utilize a hybrid multi-zone filter to induce a Hall effect-like splitting of optical Stokes skyrmions (HESSs), enabling effective separation and manipulation. By manipulating the horizontal phase gradient parameter, we independently control the separation angle of skyrmions. Additionally, we demonstrate control over the topological charge parameter to achieve symmetric and asymmetric HESSs. This effect not only enhances the manipulation capabilities of optical fields but also opens up potential applications for high precision displacement measurements and preservation quantum information.
Photonics Research
  • Publication Date: Apr. 30, 2025
  • Vol. 13, Issue 5, 1365 (2025)
Silicon Photonics
Micro-transfer printing of O-band InAs/GaAs quantum-dot SOAs on silicon photonic integrated circuits | On the Cover
Yang Liu, Jing Zhang, Laurens Bogaert, Emadreza Soltanian..., Evangelia Delli, Konstantin Morozov, Sergey Mikhrin, Johanna Rimböck, Guy Lepage, Peter Verheyen, Joris Van Campenhout, Peter Ossieur, Geert Morthier and Gunther Roelkens|Show fewer author(s)
Silicon photonics (SiPh) technology has become a key platform for developing photonic integrated circuits due to its CMOS compatibility and scalable manufacturing. However, integrating efficient on-chip optical sources and in-line amplifiers remains challenging due to silicon’s indirect bandgap. In this study, we developed prefabricated standardized InAs/GaAs quantum-dot (QD) active devices optimized for micro-transfer printing and successfully integrated them on SiPh integrated circuits. By transfer-printing standardized QD devices onto specific regions of the SiPh chip, we realized O-band semiconductor optical amplifiers (SOAs), distributed feedback (DFB) lasers, and widely tunable lasers (TLs). The SOAs reached an on-chip gain of 7.5 dB at 1299 nm and maintained stable performance across a wide input power range. The integrated DFB lasers achieved waveguide (WG)-coupled output powers of up to 19.7 mW, with a side-mode suppression ratio (SMSR) of 33.3 dB, and demonstrated notable robustness against optical feedback, supporting error-free data rates of 30 Gbps without additional isolators. Meanwhile, the TLs demonstrated a wavelength tuning range exceeding 35 nm, and a WG-coupled output power greater than 3 mW. The micro-transfer printing approach effectively decouples the fabrication of non-native devices from the SiPh process, allowing back-end integration of the III–V devices. Our approach offers a viable path toward fully integrated III–V/SiPh platforms capable of supporting high-speed, high-capacity communication.
Photonics Research
  • Publication Date: Apr. 30, 2025
  • Vol. 13, Issue 5, 1341 (2025)
Silicon Photonics
Fully reconfigurable silicon photonic MEMS microring resonators for DWDM
Ye Lu, Yinpeng Hu, Qian Ma, Yunzhi Liu..., Jiayue Zhu, Huan Li and Daoxin Dai|Show fewer author(s)
Reconfigurable silicon microrings have garnered significant interest for addressing challenges in artificial intelligence, the Internet of Things, and telecommunications due to their versatile capabilities. Compared to electro-optic (EO) and thermo-optic (TO) devices, emerging micro-electromechanical systems (MEMS)-based reconfigurable silicon photonic devices actuated by electrostatic forces offer near-zero static power consumption. This study proposes and implements novel designs for fully reconfigurable silicon photonic MEMS microrings for high-speed dense wavelength division multiplexing (DWDM) elastic networks. The designs include an all-pass microring with a 7 nm free spectral range (FSR) and full-FSR resonance tuning range, an add-drop microring with a 3.5 nm FSR and full-FSR tuning range, and an add-drop double-microring with a 34 nm FSR, wide-range discrete resonance tunability, and flat-top tunability. These advancements hold promise for practical applications.
Photonics Research
  • Publication Date: Apr. 30, 2025
  • Vol. 13, Issue 5, 1353 (2025)
Surface Optics and Plasmonics
Twisted bilayer meta-device for on-demand terahertz polarization filtering
Hui Li, Chenhui Zhao, Wenhui Xu, Jie Li..., Chenglong Zheng, Qi Tan, Chunyu Song, Hang Xu, Yun Shen and Jianquan Yao|Show fewer author(s)
Moiré meta-devices facilitate continuous and precise modulation of optical properties through the alteration of the relative alignment, such as twisting, sliding, or rotating of the metasurfaces. This capability renders them particularly suitable for dynamic applications, including zoom optics and adaptive imaging systems. Nevertheless, such designs often sacrifice more complex functionalities, such as polarization manipulation, in favor of simplicity and tunability. Here, we propose and experimentally validate a design strategy for a twisted bilayer metasurface that exhibits both varifocal capabilities and polarization filtering properties. By selecting silicon pillars with polarization-maintaining properties for Layer I and polarization-converting properties for Layer II, the designed Moiré metasurface can become sensitive to specific polarization states. Experimental results demonstrate that the proposed design can generate on-demand terahertz (THz) focused beams, achieving an average focusing efficiency exceeding 35% under x-linearly polarized (x-LP) illumination. This is accomplished by systematically varying the twisting angles p and q of Layer I in relation to Layer II in increments of 30°. Additionally, we provide numerical evidence that the focal length of the transmitted vortex beam can be adjusted using the same approach. The Moiré meta-device platform, which is engineered to modulate optical properties via mechanical twisting, obviates the necessity for external power sources or active materials. This generalized design strategy has the potential to significantly expedite the commercialization of multifunctional metasurfaces, which can produce high-precision optics across various practical applications.
Photonics Research
  • Publication Date: Apr. 21, 2025
  • Vol. 13, Issue 5, 1116 (2025)
Surface Optics and Plasmonics
Two-dimensional anomalous reflection with high efficiency and arbitrary direction based on a low-profile wideband metasurface
Huanhuan Gao, Xiaojun Huang, Zhengjie Wang, Xiongwei Ma..., Wentao Li, Hui Wang and He-Xiu Xu|Show fewer author(s)
The finding of Snell’s law for anomalous reflection enables broad applications of metasurfaces in stealth, communication, radar technology, etc. However, some unavoidable high-order modes are inherently generated due to the super lattice of this local approach, which thus causes a decrease in efficiency and a limit in the reflected angle. Here, a novel, to our knowledge, low-profile wideband reflective meta-atom shaped like a four-leaf rose is proposed to achieve a phase coverage of full 360° by varying the length of the rose leaf. Then, the genetic algorithm is adopted for the first time to encode and optimize the topology of each meta-atom on the coding metasurface to achieve two-dimensional (2D) anomalous reflection with excellent performances through an inverse design. Numerical results show that our optimized coding metasurfaces achieve a high-efficiency (90%) and large-angle (θ70° and 0°φ360°) reflection under normal incidence. For verification, far-field measurement is carried out and experimental results are consistent with the numerical ones. Our work sets up a solid platform for utilizing algorithms, especially in artificial intelligence, in the future for arbitrary 2D anomalous reflection with high efficiency and a large angle.
Photonics Research
  • Publication Date: Apr. 21, 2025
  • Vol. 13, Issue 5, 1165 (2025)
Surface Optics and Plasmonics
Light-switchable polarization conversion via an optical-fiber-controlled metasurface
Yuxi Li, Ruichao Zhu, Sai Sui, Yajuan Han..., Yuxiang Jia, Chang Ding, Shaojie Wang, Cunqian Feng, Shaobo Qu and Jiafu Wang|Show fewer author(s)
A reconfigurable metasurface based on optical control provides a control paradigm for integrating multiple functions at the same aperture, which effectively expands the freedom of control. However, the traditional light control method requires the light source to directly illuminate the photosensitive device, which forces the metasurface to be placed only according to the light emitter position, and even to need to be integrated on the light emitter, limiting the application scenarios of light-controlled reconfigurable metasurfaces. In this work, a light control method based on optical fiber is proposed, which guides and controls the light propagation path through optical fiber. The metasurface can be flexibly deployed, breaking through the limitation of physical space. As a verification, photoresistors are embedded in the metasurface, and the active device is directly excited by the light source as a driving signal to realize the switching of a polarization conversion function. The experimental results show that the optical-fiber-controlled metasurface can achieve linear-to-linear polarization conversion in the light environment and linear-to-circular polarization conversion in the dark environment. This work paves a new way, to our knowledge, to achieve a light-controlled metasurface, which enriches the family of intelligent metasurfaces and has great potential in many fields.
Photonics Research
  • Publication Date: Apr. 21, 2025
  • Vol. 13, Issue 5, 1191 (2025)

Special lssues

Innovative Optical Sensor Systems (2025)

Submission Open:15 January 2025; Submission Deadline: 30 April 2025

Editor (s): Nunzio Cennamo, Olivier Soppera, Giuseppe D’Aguanno, Yang Zhao

Structured Light: From Nanophotonics to Quantum (2025)

Submission Open:1 June 2025; Submission Deadline: 1 August 2025

Editor (s): Andrew Forbes, Haoran Ren, Lixiang Chen, Yijie Shen, Takashige Omatsu