Contents
2025
Volume: 13 Issue 4
24 Article(s)
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Research Articles
Image Processing and Image Analysis
Brain-like training of a pre-sensor optical neural network with a backpropagation-free algorithm
Zheng Huang, Conghe Wang, Caihua Zhang, Wanxin Shi... and Hongwei Chen|Show fewer author(s)
Deep learning has rapidly advanced amidst the proliferation of large models, leading to challenges in computational resources and power consumption. Optical neural networks (ONNs) offer a solution by shifting computation to optics, thereby leveraging the benefits of low power consumption, low latency, and high parallelism. The current training paradigm for ONNs primarily relies on backpropagation (BP). However, the reliance is incompatible with potential unknown processes within the system, which necessitates detailed knowledge and precise mathematical modeling of the optical process. In this paper, we present a pre-sensor multilayer ONN with nonlinear activation, utilizing a forward-forward algorithm to directly train both optical and digital parameters, which replaces the traditional backward pass with an additional forward pass. Our proposed nonlinear optical system demonstrates significant improvements in image classification accuracy, achieving a maximum enhancement of 9.0%. It also validates the efficacy of training parameters in the presence of unknown nonlinear components in the optical system. The proposed training method addresses the limitations of BP, paving the way for applications with a broader range of physical transformations in ONNs.Deep learning has rapidly advanced amidst the proliferation of large models, leading to challenges in computational resources and power consumption. Optical neural networks (ONNs) offer a solution by shifting computation to optics, thereby leveraging the benefits of low power consumption, low latency, and high parallelism. The current training paradigm for ONNs primarily relies on backpropagation (BP). However, the reliance is incompatible with potential unknown processes within the system, which necessitates detailed knowledge and precise mathematical modeling of the optical process. In this paper, we present a pre-sensor multilayer ONN with nonlinear activation, utilizing a forward-forward algorithm to directly train both optical and digital parameters, which replaces the traditional backward pass with an additional forward pass. Our proposed nonlinear optical system demonstrates significant improvements in image classification accuracy, achieving a maximum enhancement of 9.0%. It also validates the efficacy of training parameters in the presence of unknown nonlinear components in the optical system. The proposed training method addresses the limitations of BP, paving the way for applications with a broader range of physical transformations in ONNs..
Photonics Research
- Publication Date: Apr. 01, 2025
- Vol. 13, Issue 4, 915 (2025)
Imaging Systems, Microscopy, and Displays
Spatial–spectral sparse deep learning combined with a freeform lens enables extreme depth-of-field hyperspectral imaging
Yitong Pan, Zhenqi Niu, Songlin Wan, Xiaolin Li... and Chaoyang Wei|Show fewer author(s)
Traditional hyperspectral imaging (HI) systems are constrained by a limited depth of field (DoF), necessitating refocusing for any out-of-focus objects. This requirement not only slows down the imaging speed but also complicates the system architecture. It is challenging to trade off among speed, resolution, and DoF within an ultra-simple system. While some studies have reported advancements in extending DoF, the improvements remain insufficient. To address this challenge, we propose a novel, to our knowledge, differentiable framework that integrates an extended DoF (E-DoF) wave propagation model and an achromatic hyperspectral reconstructor powered by deep learning. Through rigorous experimental validation, we have demonstrated that the compact HI system is capable of snapshot capturing of high-fidelity images with an exceptional DoF reaching approximately 5 m, marking a significant improvement of over three orders of magnitude. Additionally, the system achieves over 90% spectral accuracy without aberration, nearly doubling the accuracy performance of existing methods. An asymmetric freeform surface design is introduced for diffractive optical elements, enabling dual functionality with design freedom and E-DoF. The sparse prior conditions for spatial texture and spectral features of hyperspectral cubic data are integrated into the reconstruction network, effectively mitigating texture blurring and chromatic aberration. It foresees that the optimal strategy for achromatic E-DoF can be adopted into other optical systems such as polarization imaging and depth measurement.Traditional hyperspectral imaging (HI) systems are constrained by a limited depth of field (DoF), necessitating refocusing for any out-of-focus objects. This requirement not only slows down the imaging speed but also complicates the system architecture. It is challenging to trade off among speed, resolution, and DoF within an ultra-simple system. While some studies have reported advancements in extending DoF, the improvements remain insufficient. To address this challenge, we propose a novel, to our knowledge, differentiable framework that integrates an extended DoF (E-DoF) wave propagation model and an achromatic hyperspectral reconstructor powered by deep learning. Through rigorous experimental validation, we have demonstrated that the compact HI system is capable of snapshot capturing of high-fidelity images with an exceptional DoF reaching approximately 5 m, marking a significant improvement of over three orders of magnitude. Additionally, the system achieves over 90% spectral accuracy without aberration, nearly doubling the accuracy performance of existing methods. An asymmetric freeform surface design is introduced for diffractive optical elements, enabling dual functionality with design freedom and E-DoF. The sparse prior conditions for spatial texture and spectral features of hyperspectral cubic data are integrated into the reconstruction network, effectively mitigating texture blurring and chromatic aberration. It foresees that the optimal strategy for achromatic E-DoF can be adopted into other optical systems such as polarization imaging and depth measurement..
Photonics Research
- Publication Date: Mar. 11, 2025
- Vol. 13, Issue 4, 827 (2025)
Scattering correction through Fourier-domain intensity coupling in two-photon microscopy (2P-FOCUS)
Daniel Zepeda, Yucheng Li, and Yi Xue
Light penetration depth in biological tissue is limited by tissue scattering. Correcting scattering becomes particularly challenging in scenarios with limited photon availability and when access to the transmission side of the scattering tissue is not possible. Here, we introduce, to our knowledge, a new two-photon microscopy system with Fourier-domain intensity coupling for scattering correction (2P-FOCUS). 2P-FOCUS corrects scattering by intensity modulation in the Fourier domain, leveraging the nonlinearity of multiple-beam interference and two-photon excitation, eliminating the need for a guide star, iterative optimization, or measuring transmission or reflection matrices. 2P-FOCUS uses random patterns to probe scattering properties, combined with a single-shot algorithm to rapidly generate the correction mask. 2P-FOCUS can also correct scattering beyond the limitation of the memory effect by automatically customizing correction masks for each subregion in a large field-of-view. We provide several proof-of-principle demonstrations here, including focusing and imaging through a bone sample, and imaging neurons and cerebral blood vessels in the mouse brain ex vivo. 2P-FOCUS significantly enhances two-photon fluorescence signals by several tens of folds compared to cases without scattering correction at the same excitation power. 2P-FOCUS can also correct tissue scattering over a 230 μm×230 μm×510 μm volume, which is beyond the memory effect range. 2P-FOCUS is able to measure, calculate, and correct scattering within a few seconds, effectively delivering more light deep into the scattering tissue. 2P-FOCUS could be broadly adopted for deep tissue imaging owing to its powerful combination of effectiveness, speed, and cost.Light penetration depth in biological tissue is limited by tissue scattering. Correcting scattering becomes particularly challenging in scenarios with limited photon availability and when access to the transmission side of the scattering tissue is not possible. Here, we introduce, to our knowledge, a new two-photon microscopy system with Fourier-domain intensity coupling for scattering correction (2P-FOCUS). 2P-FOCUS corrects scattering by intensity modulation in the Fourier domain, leveraging the nonlinearity of multiple-beam interference and two-photon excitation, eliminating the need for a guide star, iterative optimization, or measuring transmission or reflection matrices. 2P-FOCUS uses random patterns to probe scattering properties, combined with a single-shot algorithm to rapidly generate the correction mask. 2P-FOCUS can also correct scattering beyond the limitation of the memory effect by automatically customizing correction masks for each subregion in a large field-of-view. We provide several proof-of-principle demonstrations here, including focusing and imaging through a bone sample, and imaging neurons and cerebral blood vessels in the mouse brain ex vivo. 2P-FOCUS significantly enhances two-photon fluorescence signals by several tens of folds compared to cases without scattering correction at the same excitation power. 2P-FOCUS can also correct tissue scattering over a
Photonics Research
- Publication Date: Mar. 11, 2025
- Vol. 13, Issue 4, 845 (2025)
Compact spectral-polarization-modulation method for rapid and versatile polarization measurements in interferometric imaging
Di Yang, Weike Wang, Songwen Xu, Zhuoqun Yuan, and Yanmei Liang
Polarization-based detection technologies have broad applications across various fields. Integrating polarization with interferometric imaging holds significant promise for simultaneously capturing three-dimensional structure and polarization information. However, existing interferometric polarization measurement methods often rely on complex setups and sacrifice the acquisition rate or axial imaging range for parameter diversity. In this study, we presented an efficient and compact interferometric polarization measurement method based on spectral-polarization-modulation (SPM) and integrated it with optical coherence tomography (OCT) to construct an advancing interferometric imaging system called SPM-OCT. This method can extract birefringent and dichroic parameters from the polarization-modulated signal without reducing the acquisition rate or the axial imaging range. Imaging experiments on standard polarization elements, biological tissues, and gold nanorod (GNR) phantoms demonstrated that our proposed method provided accurate birefringent and dichroic parameters and avoided phase jump errors. Especially, the dichroic parameters obtained from our system can distinguish GNRs from biological tissues with high contrast. Overall, the rapid and simple polarization measurement of the SPM method is expected to advance the interferometric imaging method and inspire new research directions in polarization measurement technology.Polarization-based detection technologies have broad applications across various fields. Integrating polarization with interferometric imaging holds significant promise for simultaneously capturing three-dimensional structure and polarization information. However, existing interferometric polarization measurement methods often rely on complex setups and sacrifice the acquisition rate or axial imaging range for parameter diversity. In this study, we presented an efficient and compact interferometric polarization measurement method based on spectral-polarization-modulation (SPM) and integrated it with optical coherence tomography (OCT) to construct an advancing interferometric imaging system called SPM-OCT. This method can extract birefringent and dichroic parameters from the polarization-modulated signal without reducing the acquisition rate or the axial imaging range. Imaging experiments on standard polarization elements, biological tissues, and gold nanorod (GNR) phantoms demonstrated that our proposed method provided accurate birefringent and dichroic parameters and avoided phase jump errors. Especially, the dichroic parameters obtained from our system can distinguish GNRs from biological tissues with high contrast. Overall, the rapid and simple polarization measurement of the SPM method is expected to advance the interferometric imaging method and inspire new research directions in polarization measurement technology..
Photonics Research
- Publication Date: Mar. 31, 2025
- Vol. 13, Issue 4, 1049 (2025)
Instrumentation and Measurements
Transforming optical Vernier effect into coherent microwave interference towards highly sensitive optical fiber sensing
Ruimin Jie, Jie Huang, and Chen Zhu
The optical Vernier effect has garnered significant research attention and found widespread applications in enhancing the measurement sensitivity of optical fiber interferometric sensors. Typically, Vernier sensor interrogation involves measuring its optical spectrum across a wide wavelength range using a high-precision spectrometer. This process is further complicated by the intricate signal processing required for accurately extracting the Vernier envelope, which can inadvertently introduce errors that compromise sensing performance. In this work, we introduce a novel approach to interrogating Vernier sensors based on a coherent microwave interference-assisted measurement technique. Instead of measuring the optical spectrum, we acquire the frequency response of the Vernier optical fiber sensor using a vector network analyzer. This response includes a characteristic notch that is highly sensitive to external perturbations. We discuss in detail the underlying physics of coherent microwave interference-based notch generation and the sensing principle. As a proof of concept, we construct a Vernier sensor using two air-gap Fabry–Perot interferometers arranged in parallel, demonstrating high-sensitivity strain sensing through microwave-domain measurements. The introduced technique is straightforward to implement, and the characteristic sensing signal is easy to demodulate and highly sensitive, presenting an excellent solution to the complexities of existing optical Vernier sensor systems.The optical Vernier effect has garnered significant research attention and found widespread applications in enhancing the measurement sensitivity of optical fiber interferometric sensors. Typically, Vernier sensor interrogation involves measuring its optical spectrum across a wide wavelength range using a high-precision spectrometer. This process is further complicated by the intricate signal processing required for accurately extracting the Vernier envelope, which can inadvertently introduce errors that compromise sensing performance. In this work, we introduce a novel approach to interrogating Vernier sensors based on a coherent microwave interference-assisted measurement technique. Instead of measuring the optical spectrum, we acquire the frequency response of the Vernier optical fiber sensor using a vector network analyzer. This response includes a characteristic notch that is highly sensitive to external perturbations. We discuss in detail the underlying physics of coherent microwave interference-based notch generation and the sensing principle. As a proof of concept, we construct a Vernier sensor using two air-gap Fabry–Perot interferometers arranged in parallel, demonstrating high-sensitivity strain sensing through microwave-domain measurements. The introduced technique is straightforward to implement, and the characteristic sensing signal is easy to demodulate and highly sensitive, presenting an excellent solution to the complexities of existing optical Vernier sensor systems..
Photonics Research
- Publication Date: Mar. 25, 2025
- Vol. 13, Issue 4, 875 (2025)
Integrated Optics
High-linearity wide-bandwidth integrated thin-film lithium niobate modulator based on a dual-optical-mode co-modulated configuration
Heyun Tan, Junwei Zhang, Jingyi Wang, Songnian Fu... and Xinlun Cai|Show fewer author(s)
High-linearity electro-optic (EO) modulators play a crucial role in microwave photonics (MWP). Although various methods have been explored to enhance linearity in MWP links, they are often constrained by the intrinsic nonlinearity of modulator materials, the complexity of external control devices, the bulkiness of structures, and bandwidth limitations. In this study, we present an integrated thin-film lithium niobate (TFLN) linear Mach–Zehnder modulator (LMZM), showing, to our knowledge, a record-high spurious-free dynamic range (SFDR) of 121.7 dB·Hz4/5 at 1 GHz with an optical power (OP) of 5.5 dBm into the photodetector (PD), based on a wide-bandwidth (>50 GHz) dual-optical-mode (TE0 and TE1) co-modulated configuration with just one RF input. Additionally, compared to conventional MZMs (CMZMs), the LMZM exhibits a >10.6-dB enhancement in SFDR with an OP of >-8 dBm at 1 GHz, and maintains a 6.07-dB SFDR improvement even at 20 GHz with an OP of 0 dBm. The novel LMZM, featuring high linearity, wide bandwidth, structural simplicity, and high integration, holds significant potential as a key component in future large-scale and high-performance MWP integrated circuits.High-linearity electro-optic (EO) modulators play a crucial role in microwave photonics (MWP). Although various methods have been explored to enhance linearity in MWP links, they are often constrained by the intrinsic nonlinearity of modulator materials, the complexity of external control devices, the bulkiness of structures, and bandwidth limitations. In this study, we present an integrated thin-film lithium niobate (TFLN) linear Mach–Zehnder modulator (LMZM), showing, to our knowledge, a record-high spurious-free dynamic range (SFDR) of
Photonics Research
- Publication Date: Mar. 11, 2025
- Vol. 13, Issue 4, 817 (2025)
Multi-channel Hong–Ou–Mandle interference between independent comb-based weak coherent pulses
Long Huang, Linhan Tang, Yang Wang, Minhui Cheng... and Wenfu Zhang|Show fewer author(s)
With the widespread application of quantum communication technology, there is an urgent need to enhance unconditionally secure key rates and capacity. Measurement-device-independent quantum key distribution (MDI-QKD), proven to be immune to detection-side channel attacks, is a secure and reliable quantum communication scheme. The core of this scheme is Hong–Ou–Mandle (HOM) interference, a quantum optical phenomenon with no classical analog, where identical photons meeting on a symmetric beam splitter (BS) undergo interference and bunching. Any differences in the degrees of freedom (frequency, arrival time, spectrum, polarization, and the average number of photons per pulse) between the photons will deteriorate the interference visibility. Here, we demonstrate 16-channel weak coherent pulses (WCPs) of HOM interference with all channels’ interference visibility over 46% based on two independent frequency-post-aligned soliton microcombs (SMCs). In our experiment, full locking and frequency alignment of the comb teeth between the two SMCs were achieved through pump frequency stabilization, SMC repetition rate locking, and fine tuning of the repetition rate. This demonstrates the feasibility of using independently generated SMCs as multi-wavelength sources for quantum communication. Meanwhile, SMC can achieve hundreds of frequency-stable comb teeth by locking only two parameters, which further reduces the complexity of frequency locking and the need for finding sufficient suitable frequency references compared to independent laser arrays.With the widespread application of quantum communication technology, there is an urgent need to enhance unconditionally secure key rates and capacity. Measurement-device-independent quantum key distribution (MDI-QKD), proven to be immune to detection-side channel attacks, is a secure and reliable quantum communication scheme. The core of this scheme is Hong–Ou–Mandle (HOM) interference, a quantum optical phenomenon with no classical analog, where identical photons meeting on a symmetric beam splitter (BS) undergo interference and bunching. Any differences in the degrees of freedom (frequency, arrival time, spectrum, polarization, and the average number of photons per pulse) between the photons will deteriorate the interference visibility. Here, we demonstrate 16-channel weak coherent pulses (WCPs) of HOM interference with all channels’ interference visibility over 46% based on two independent frequency-post-aligned soliton microcombs (SMCs). In our experiment, full locking and frequency alignment of the comb teeth between the two SMCs were achieved through pump frequency stabilization, SMC repetition rate locking, and fine tuning of the repetition rate. This demonstrates the feasibility of using independently generated SMCs as multi-wavelength sources for quantum communication. Meanwhile, SMC can achieve hundreds of frequency-stable comb teeth by locking only two parameters, which further reduces the complexity of frequency locking and the need for finding sufficient suitable frequency references compared to independent laser arrays..
Photonics Research
- Publication Date: Mar. 11, 2025
- Vol. 13, Issue 4, 837 (2025)
On-chip tunable single-mode high-power narrow-linewidth Fabry–Perot microcavity laser on Yb3+-doped thin-film lithium niobate
Qinfen Huang, Zhiwei Fang, Zhe Wang, Yiran Zhu... and Ya Cheng|Show fewer author(s)
Ytterbium ion (Yb3+)-doped lasers are widely used in precision machining and precision measurement fields because of their high efficiency and high power, which are primarily based on solid-state lasers and fiber lasers. Here, we demonstrate an on-chip Yb3+-doped thin-film lithium niobate (Yb:TFLN) Fabry–Perot microcavity laser. We achieve single-frequency laser operation at 1030 and 1060 nm with a side-mode suppression ratio above 30 dB, an emission linewidth below 40 pm, and an output power up to 1.5 mW at 1060 nm and 0.3 mW at 1030 nm. In addition, using the electro-optic effect of lithium niobate, we achieve a laser tuning efficiency of 4 pm/V. This work opens the path to on-chip high-power and mode-locked ultrafast laser output.Ytterbium ion (
Photonics Research
- Publication Date: Apr. 01, 2025
- Vol. 13, Issue 4, 935 (2025)
Lasers and Laser Optics
All-solid-state miniature laser gyroscope based on a single monolithic non-planar ring oscillator
Danqing Liu, Changlei Guo, Chunzhao Ma, Weitong Fan... and Hsien-Chi Yeh|Show fewer author(s)
He-Ne gaseous ring-laser gyroscopes (RLGs) have brought great breakthroughs in numbers of fields such as inertial navigation and attitude control in the past 50 years. However, their counterparts of all-solid-state, active RLGs have been far behind even though they have a few indispensable advantages. Here, we propose and demonstrate an all-solid-state, active RLG based on a millimeter-sized, single monolithic non-planar ring oscillator (NPRO) with a gain medium of Nd:YAG crystal or Nd-glass. The clockwise (CW) and counter-clockwise (CCW) laser modes in NPRO are simultaneously initiated under a regime of laser feedback interferometry, whose nonzero frequency difference intrinsically formats the single monolithic NPRO working as a Sagnac laser gyroscope without a noticeable lock-in effect. The higher wavefront distortion in NPRO samples is revealed to introduce less mode competition (higher beat frequency stability) between the two laser modes, which is a precondition to build the NPRO gyroscope. Under a free-running condition, the NPRO gyroscope typically has a bias instability of 31.3 deg/h and an angle random walk of 0.22 deg/h with a scale factor of 38.3 Hz/(deg s-1), and the instability is mainly caused by the magnetic noise at present. The NPRO gyroscope can be enclosed in a centimeter-sized package, with a power consumption below 0.7 W and a mass under 20 g. Moreover, the stability performance can be further improved by NPRO design and active noise suppression in the future. Such compact, low-power-consumed, and highly stable RLGs may find important applications in aerospace, defense, and industry.He-Ne gaseous ring-laser gyroscopes (RLGs) have brought great breakthroughs in numbers of fields such as inertial navigation and attitude control in the past 50 years. However, their counterparts of all-solid-state, active RLGs have been far behind even though they have a few indispensable advantages. Here, we propose and demonstrate an all-solid-state, active RLG based on a millimeter-sized, single monolithic non-planar ring oscillator (NPRO) with a gain medium of Nd:YAG crystal or Nd-glass. The clockwise (CW) and counter-clockwise (CCW) laser modes in NPRO are simultaneously initiated under a regime of laser feedback interferometry, whose nonzero frequency difference intrinsically formats the single monolithic NPRO working as a Sagnac laser gyroscope without a noticeable lock-in effect. The higher wavefront distortion in NPRO samples is revealed to introduce less mode competition (higher beat frequency stability) between the two laser modes, which is a precondition to build the NPRO gyroscope. Under a free-running condition, the NPRO gyroscope typically has a bias instability of
Photonics Research
- Publication Date: Apr. 01, 2025
- Vol. 13, Issue 4, 897 (2025)
Medical Optics and Biotechnology
Fast parallel quantification for near-infrared genetically encoded reporters with self-calibrated photoacoustic screening
Xuanhao Wang, Yan Luo, Fudong Xue, Lijuan Ma... and Cheng Ma|Show fewer author(s)
The integration of near-infrared genetically encoded reporters (NIR-GERs) with photoacoustic (PA) imaging enables visualizing deep-seated functions of specific cell populations at high resolution, though the imaging depth is primarily constrained by reporters’ PA response intensity. Directed evolution can optimize NIR-GERs’ performance for PA imaging, yet precise quantifying of PA responses in mutant proteins expressed in E. coli colonies across iterative rounds poses challenges to the imaging speed and quantification capabilities of the screening platforms. Here, we present self-calibrated photoacoustic screening (SCAPAS), an imaging-based platform that can detect samples in parallel within 5 s (equivalent to 50 ms per colony), achieving a considerable quantification accuracy of approximately 2.8% and a quantification precision of about 6.47%. SCAPAS incorporates co-expressed reference proteins in sample preparation and employs a ring transducer array with switchable illumination for rapid, wide-field dual-wavelength PA imaging, enabling precisely calculating the PA response using the self-calibration method. Numerical simulations validated the image optimization strategy, quantification process, and noise robustness. Tests with co-expression samples confirmed SCAPAS’s superior screening speed and quantification capabilities. We believe that SCAPAS will facilitate the development of novel NIR-GERs suitable for PA imaging and has the potential to significantly impact the advancement of PA probes and molecular imaging.The integration of near-infrared genetically encoded reporters (NIR-GERs) with photoacoustic (PA) imaging enables visualizing deep-seated functions of specific cell populations at high resolution, though the imaging depth is primarily constrained by reporters’ PA response intensity. Directed evolution can optimize NIR-GERs’ performance for PA imaging, yet precise quantifying of PA responses in mutant proteins expressed in E. coli colonies across iterative rounds poses challenges to the imaging speed and quantification capabilities of the screening platforms. Here, we present self-calibrated photoacoustic screening (SCAPAS), an imaging-based platform that can detect samples in parallel within 5 s (equivalent to 50 ms per colony), achieving a considerable quantification accuracy of approximately 2.8% and a quantification precision of about 6.47%. SCAPAS incorporates co-expressed reference proteins in sample preparation and employs a ring transducer array with switchable illumination for rapid, wide-field dual-wavelength PA imaging, enabling precisely calculating the PA response using the self-calibration method. Numerical simulations validated the image optimization strategy, quantification process, and noise robustness. Tests with co-expression samples confirmed SCAPAS’s superior screening speed and quantification capabilities. We believe that SCAPAS will facilitate the development of novel NIR-GERs suitable for PA imaging and has the potential to significantly impact the advancement of PA probes and molecular imaging..
Photonics Research
- Publication Date: Apr. 01, 2025
- Vol. 13, Issue 4, 941 (2025)
Nanophotonics and Photonic Crystals
Observation of multiple quasi-bound states in the continuum by symmetry breaking in a photonic crystal slab
Shuangli Li, Lujun Huang, Haozong Zhong, Minghao Ning... and Lin Li|Show fewer author(s)
Bound states in the continuum (BICs) open up a unique avenue of enhancing light–matter interactions due to their extreme field confinement and infinite quality (Q) factors. Although tremendous progress has been made in the past 10 years, the majority of previous works focused on either a single BIC or dual BICs. In this work, we present both theoretical investigation and experimental demonstration on multiple BICs in a photonic crystal slab with a hexagonal lattice. All of these BICs at Γ-point can be categorized as symmetry-protected (SP) BICs. Furthermore, two BICs belong to merging BICs with topological charges q=-2. Breaking the structural symmetry will split these BICs with q=-2 into two accidental BICs with q=-1. While the other two are different from the former two, the Q-factors of both modes at the Γ-point retain a stably ultrahigh value (Q>108) when the circular hole is transformed into a rotated elliptical hole with different size ratios of semi-long and semi-short axes. In addition, the Q-factors of the latter two BICs decrease rapidly with kx, indicating that the quasi-BICs become accessible at an ultra-small incident angle. We also show that the Q-factors of the former two BICs exhibit different dependence on the asymmetry parameters, suggesting a viable way of realizing high-Q resonances at multi-wavelengths. Finally, we presented experimental demonstration of four high-Q quasi-BICs at four different wavelengths in the near infrared by fabricating a series of photonic crystal slabs made of rotated elliptical holes and characterizing their reflection spectra. We showed that most of the measured Q-factors are above 1000 for four quasi-BICs, and the highest one can reach 16,764. Our results may find promising applications in sum-frequency generation, four-wave mixing, multiband sensing, lasing, etc.Bound states in the continuum (BICs) open up a unique avenue of enhancing light–matter interactions due to their extreme field confinement and infinite quality (
Photonics Research
- Publication Date: Apr. 01, 2025
- Vol. 13, Issue 4, 968 (2025)
Bilayer MoS2 nanoribbons: observation of optically inactive “exciton-free” regions and electrical gating of optical response
V. G. Kravets, Zhaolong Chen, Yashar Mayamei, K. S. Novoselov, and A. N. Grigorenko
Due to large anisotropy and tunable exciton transitions observed in visible light, transition metal dichalcogenides could become platform materials for on-chip next-generation photonics and nano-optics. For this to happen, one needs to be able to nanostructure transition metal dichalcogenides without losing their optical properties. However, both our understanding of the physics of such nanostructures and their technology are still at infancy and, therefore, experimental works on optics of transition metal dichalcogenides nanostructures are urgently required. Here, we study optical characteristics of bilayer MoS2 nanoribbons by measuring reflection and photoluminescence of nanostructured bilayer MoS2 flakes near exciton transitions. We show that there exist optically inactive “exciton-free” regions near the edges of nanoribbons with sizes of around 10 nm. We demonstrate that the “exciton-free” regions can be controlled by external electrical gating. These results are important for nanostructured optoelectronic devices made of MoS2 and other transition metal dichalcogenides.Due to large anisotropy and tunable exciton transitions observed in visible light, transition metal dichalcogenides could become platform materials for on-chip next-generation photonics and nano-optics. For this to happen, one needs to be able to nanostructure transition metal dichalcogenides without losing their optical properties. However, both our understanding of the physics of such nanostructures and their technology are still at infancy and, therefore, experimental works on optics of transition metal dichalcogenides nanostructures are urgently required. Here, we study optical characteristics of bilayer
Photonics Research
- Publication Date: Apr. 01, 2025
- Vol. 13, Issue 4, 1021 (2025)
Optical Devices
All-fiber orbital-angular-momentum mode encoding system based on helical fiber gratings
Yu Chen, Ming Gao, Yutao Wang, Xinyue Huang... and Hongpu Li|Show fewer author(s)
In this study, we propose and demonstrate an all-fiber orbital-angular-momentum (OAM) mode encoding system, where through helical fiber gratings (HFGs), binary symbols are encoded to or decoded from two OAM modes with topological charges (TCs) of -1 and +1, respectively. We experimentally validate that the OAM mode generated by a clockwise-helix HFG (cHFG) can be converted back into fundamental mode by using an HFG with a helix orientation opposite to that of the cHFG, i.e., ccHFG. Benefited from utilization of the HFGs, the proposed OAM mode encoding system has a low cost, low insertion loss, high mode conversion efficiency, and polarization independence. To the best of our knowledge, this is the first demonstration of the HFGs-based all-fiber OAM mode encoding/decoding scheme, which may find potential applications in optical communication and quantum communication as well.In this study, we propose and demonstrate an all-fiber orbital-angular-momentum (OAM) mode encoding system, where through helical fiber gratings (HFGs), binary symbols are encoded to or decoded from two OAM modes with topological charges (TCs) of
Photonics Research
- Publication Date: Apr. 01, 2025
- Vol. 13, Issue 4, 960 (2025)
High-efficiency multi-channel focusing and imaging enabled by polarization-frequency multiplexing non-interleaved metasurfaces
Xunjun He, Mingzhong Wu, Guangjun Lu, Ying Zhang, and Zhaoxin Geng
In microwave communication systems, focusing and imaging have attracted widespread attention due to their application prospects in the information processing and communication fields. Most existing multi-channel focusing and imaging are implemented by interleaved metasurfaces. However, the disadvantages of their large size and low efficiency limit their practical applications in large-capacity and low-loss integrated systems. To solve these issues, here, we propose a non-interleaved polarization-frequency multiplexing metasurface for high-efficiency multi-channel focusing and imaging. The meta-atoms of the non-interleaved metasurface are composed of a metallic ground plate, two dielectric layers, a larger cross-shaped metal structure, and a smaller cross-shaped metal structure embedded by a circular metal aperture. By altering the size of two cross-shaped structures, the designed meta-atom can obtain the independent complete 2π phase coverage with high reflection efficiency at two different frequency ranges for two orthogonal linear polarization (LP) incidences, realizing polarization multiplexing and frequency multiplexing. Moreover, two types of metasurfaces based on the above meta-atoms are designed to realize multi-channel focusing and imaging with high efficiency. As a proof, the focusing metasurface is fabricated and measured, and the measured results are well consistent with simulated results. Therefore, the proposed scheme has the advantages of high efficiency, multi-channel, and compact size, which possesses broad application prospects in low-loss and multi-channel communication integrated systems.In microwave communication systems, focusing and imaging have attracted widespread attention due to their application prospects in the information processing and communication fields. Most existing multi-channel focusing and imaging are implemented by interleaved metasurfaces. However, the disadvantages of their large size and low efficiency limit their practical applications in large-capacity and low-loss integrated systems. To solve these issues, here, we propose a non-interleaved polarization-frequency multiplexing metasurface for high-efficiency multi-channel focusing and imaging. The meta-atoms of the non-interleaved metasurface are composed of a metallic ground plate, two dielectric layers, a larger cross-shaped metal structure, and a smaller cross-shaped metal structure embedded by a circular metal aperture. By altering the size of two cross-shaped structures, the designed meta-atom can obtain the independent complete
Photonics Research
- Publication Date: Apr. 01, 2025
- Vol. 13, Issue 4, 976 (2025)
Optoelectronics
Reverse Smith-Purcell radiation in photonic crystals
Xiaoqiuyan Zhang, Sunchao Huang, Tianyu Zhang, Yuxuan Zhuang... and Min Hu|Show fewer author(s)
Free electron radiation, particularly Smith-Purcell radiation, provides a versatile platform for exploring light-matter interactions and generating light sources. A fundamental characteristic of Smith-Purcell radiation is the monotonic decrease in radiation frequency as the observation angle increases relative to the direction of the free electrons’ motion, akin to the Doppler effect. Here, we demonstrate that this fundamental characteristic can be altered in Smith-Purcell radiation generated by photonic crystals with left-handed properties. Specifically, we have achieved, to our knowledge, a novel phenomenon that the lower-frequency components propagate forward, while the higher-frequency components propagate backward, which we define as reverse Smith-Purcell radiation. Additionally, this reverse Smith-Purcell radiation can confine the radiation to a narrow angular range, which provides a way to obtain broadband light sources in a specific observation angle. Furthermore, by precisely adjusting the grating geometry and the kinetic energy of the free electrons, we can control both the radiation direction and the output frequencies. Our results provide a promising platform to study unexplored light-matter interactions and open avenues to obtain tunable, broadband light sources.Free electron radiation, particularly Smith-Purcell radiation, provides a versatile platform for exploring light-matter interactions and generating light sources. A fundamental characteristic of Smith-Purcell radiation is the monotonic decrease in radiation frequency as the observation angle increases relative to the direction of the free electrons’ motion, akin to the Doppler effect. Here, we demonstrate that this fundamental characteristic can be altered in Smith-Purcell radiation generated by photonic crystals with left-handed properties. Specifically, we have achieved, to our knowledge, a novel phenomenon that the lower-frequency components propagate forward, while the higher-frequency components propagate backward, which we define as reverse Smith-Purcell radiation. Additionally, this reverse Smith-Purcell radiation can confine the radiation to a narrow angular range, which provides a way to obtain broadband light sources in a specific observation angle. Furthermore, by precisely adjusting the grating geometry and the kinetic energy of the free electrons, we can control both the radiation direction and the output frequencies. Our results provide a promising platform to study unexplored light-matter interactions and open avenues to obtain tunable, broadband light sources..
Photonics Research
- Publication Date: Mar. 31, 2025
- Vol. 13, Issue 4, 1060 (2025)
Physical Optics
Floquet engineering with spatially nonuniform driving fields
Stella T. Schindler, and Hanan Herzig Sheinfux
In Floquet engineering, we apply a time-periodic modulation to change the effective behavior of a wave system. In this work, we generalize Floquet engineering to more fully exploit spatial degrees of freedom, expanding the scope of effective behaviors we can access. We develop a perturbative procedure to engineer space-time dependent driving forces that effectively transform broad classes of tight-binding systems into one another. We demonstrate several applications, including removing disorder, undoing Anderson localization, and enhancing localization to an extreme in spatially modulated waveguides. This procedure straightforwardly extends to other types of physical systems and different Floquet driving field implementations.In Floquet engineering, we apply a time-periodic modulation to change the effective behavior of a wave system. In this work, we generalize Floquet engineering to more fully exploit spatial degrees of freedom, expanding the scope of effective behaviors we can access. We develop a perturbative procedure to engineer space-time dependent driving forces that effectively transform broad classes of tight-binding systems into one another. We demonstrate several applications, including removing disorder, undoing Anderson localization, and enhancing localization to an extreme in spatially modulated waveguides. This procedure straightforwardly extends to other types of physical systems and different Floquet driving field implementations..
Photonics Research
- Publication Date: Apr. 01, 2025
- Vol. 13, Issue 4, 905 (2025)
Spin angular momentum engineering within highly localized focal fields: from simple orientation to complex topologies
Yongxi Zeng, Yanzhong Yu, Jian Chen, Houan Teng... and Qiwen Zhan|Show fewer author(s)
Optical skyrmions, as quasiparticles with non-trivial topological structures, have garnered significant attention in recent years. This paper proposes a method for customized spin angular momentum (SAM) distribution in highly localized focal fields, thereby enabling the generation of SAM skyrmion and bimeron topologies. The skyrmionic SAM textures can be flexibly controlled, such as polarity, vorticity, and helicity. In addition, the two-dimensional projection plane can be arbitrarily oriented within three-dimensional space. By utilizing time-reversal techniques, we obtain the required illumination fields of the 4π-focusing system and subsequently evaluate the tightly focused field using vector Debye integral theory. Our results show that the SAM orientation within the focal field is controlled by the orientation of orthogonal dipole pairs. Using the radiation field of a multi-concentric array of orthogonal dipole pairs, the distribution of SAM orientation in the target plane can be tailored to generate SAM topological structures such as skyrmions and bimerons. Highly localized and tunable SAM engineering holds great potential for applications in optical manipulation, light–matter interactions, optical information processing, transmission, and storage.Optical skyrmions, as quasiparticles with non-trivial topological structures, have garnered significant attention in recent years. This paper proposes a method for customized spin angular momentum (SAM) distribution in highly localized focal fields, thereby enabling the generation of SAM skyrmion and bimeron topologies. The skyrmionic SAM textures can be flexibly controlled, such as polarity, vorticity, and helicity. In addition, the two-dimensional projection plane can be arbitrarily oriented within three-dimensional space. By utilizing time-reversal techniques, we obtain the required illumination fields of the
Photonics Research
- Publication Date: Apr. 01, 2025
- Vol. 13, Issue 4, 995 (2025)
Quantum Optic
Spin-momentum-mixing interactions with cavity-mediated supersolid in spinor condensates
Jingjun You, Su Yi, and Yuangang Deng
Ultracold atoms with cavity-mediated long-range interactions offer a promising platform for exploring emergent quantum phenomena. Building on recent experimental progress, we propose a novel scheme to create supersolid square and plane wave phases in spin-1/2 condensates. We demonstrate that the self-ordered supersolid phase supports an undamped gapless Goldstone mode across a broad parameter regime. This proposal is comprehensively described by the two-component Tavis–Cummings model with hosting a U(1) symmetry. By exploiting the superradiant photon-exchange process, our approach also constructs the cavity-mediated spin-momentum-mixing interactions between highly correlated spin and momentum modes, which may open avenues for exploring spin-momentum squeezing and spatially distributed multipartite entanglement.Ultracold atoms with cavity-mediated long-range interactions offer a promising platform for exploring emergent quantum phenomena. Building on recent experimental progress, we propose a novel scheme to create supersolid square and plane wave phases in spin-1/2 condensates. We demonstrate that the self-ordered supersolid phase supports an undamped gapless Goldstone mode across a broad parameter regime. This proposal is comprehensively described by the two-component Tavis–Cummings model with hosting a
Photonics Research
- Publication Date: Apr. 01, 2025
- Vol. 13, Issue 4, 987 (2025)
Silicon Photonics
Multi-beam top-facing optical phased array enabling a 360° field of view
Jinling Guo, Weilun Zhang, Zichun Liao, Chi Zhang... and Xinliang Zhang|Show fewer author(s)
An optical phased array (OPA) featuring all-solid-state beam steering is a promising component for light detection and ranging (LiDAR). There exists an increasing demand for panoramic perception and rapid target recognition in intricate LiDAR applications, such as security systems and self-driving vehicles. However, the majority of existing OPA approaches suffer from limitations in field of view (FOV) and do not explore parallel scanning, thus restricting their potential utility. Here, we combine a two-dimensional (2D) grating with an FOV-synthetization concept to design a silicon-based top-facing OPA for realizing a wide cone-shaped 360° FOV. By utilizing four OPA units sharing the 2D grating as a single emitter, four laser beams are simultaneously emitted upwards and manipulated to scan distinct regions, demonstrating seamless beam steering within the lateral 360° range. Furthermore, a frequency-modulated dissipative Kerr-soliton (DKS) microcomb is applied to the proposed multi-beam OPA, exhibiting its capability in large-scale parallel multi-target coherent detection. The comb lines are spatially dispersed with a 2D grating and separately measure distances and velocities in parallel, significantly enhancing the parallelism. The results showcase a ranging precision of 1 cm and velocimetry errors of less than 0.5 cm/s. This approach provides an alternative solution for LiDAR with an ultra-wide FOV and massively parallel multi-target detection capability.An optical phased array (OPA) featuring all-solid-state beam steering is a promising component for light detection and ranging (LiDAR). There exists an increasing demand for panoramic perception and rapid target recognition in intricate LiDAR applications, such as security systems and self-driving vehicles. However, the majority of existing OPA approaches suffer from limitations in field of view (FOV) and do not explore parallel scanning, thus restricting their potential utility. Here, we combine a two-dimensional (2D) grating with an FOV-synthetization concept to design a silicon-based top-facing OPA for realizing a wide cone-shaped 360° FOV. By utilizing four OPA units sharing the 2D grating as a single emitter, four laser beams are simultaneously emitted upwards and manipulated to scan distinct regions, demonstrating seamless beam steering within the lateral 360° range. Furthermore, a frequency-modulated dissipative Kerr-soliton (DKS) microcomb is applied to the proposed multi-beam OPA, exhibiting its capability in large-scale parallel multi-target coherent detection. The comb lines are spatially dispersed with a 2D grating and separately measure distances and velocities in parallel, significantly enhancing the parallelism. The results showcase a ranging precision of 1 cm and velocimetry errors of less than 0.5 cm/s. This approach provides an alternative solution for LiDAR with an ultra-wide FOV and massively parallel multi-target detection capability..
Photonics Research
- Publication Date: Apr. 01, 2025
- Vol. 13, Issue 4, 889 (2025)
Dilated space-and-wavelength selective crosspoint optical switch
Ziyao Zhang, Minjia Chen, Rui Ma, Bohao Sun... and Qixiang Cheng|Show fewer author(s)
Photonic integrated switches that are both space and wavelength selective are a highly promising technology for data-intensive applications as they benefit from multi-dimensional manipulation of optical signals. However, scaling these switches normally poses stringent challenges such as increased fabrication complexity and control difficulties, due to the growing number of switching elements. In this work, we propose a new type of dilated crosspoint topology, which efficiently handles both space and wavelength selective switching, while reducing the required switching element count by an order of magnitude compared to reported designs. To the best of our knowledge, our design requires the fewest switching elements for an equivalent routing paths number and it fully cancels the first-order in-band crosstalk. We demonstrate such an ultra-compact space-and-wavelength selective switch (SWSS) at a scale of 4×4×4λ on the silicon-on-insulator (SOI) platform. Experimental results reveal that the switch achieves an insertion loss ranging from 2.3 dB to 8.6 dB and crosstalk levels in between -35.3 dB and -59.7 dB. The add-drop microring-resonators (MRRs) are equipped with micro-heaters, exhibiting a rise and fall time of 46 μs and 0.33 μs, respectively. These performance characteristics highlight the switch’s ultra-low element count and crosstalk with low insertion loss, making it a promising candidate for advanced data center applications.Photonic integrated switches that are both space and wavelength selective are a highly promising technology for data-intensive applications as they benefit from multi-dimensional manipulation of optical signals. However, scaling these switches normally poses stringent challenges such as increased fabrication complexity and control difficulties, due to the growing number of switching elements. In this work, we propose a new type of dilated crosspoint topology, which efficiently handles both space and wavelength selective switching, while reducing the required switching element count by an order of magnitude compared to reported designs. To the best of our knowledge, our design requires the fewest switching elements for an equivalent routing paths number and it fully cancels the first-order in-band crosstalk. We demonstrate such an ultra-compact space-and-wavelength selective switch (SWSS) at a scale of
Photonics Research
- Publication Date: Apr. 01, 2025
- Vol. 13, Issue 4, 924 (2025)
Spectroscopy
Single-photon super-resolved spectroscopy from spatial-mode demultiplexing
Luigi Santamaria, Fabrizio Sgobba, Deborah Pallotti, and Cosmo Lupo
We demonstrate the spectroscopy of incoherent light with subdiffraction resolution. In a proof-of-principle experiment, we analyze the spectrum of a pair of incoherent pointlike sources whose separation is below the diffraction limit. The two sources mimic a planetary system, with a brighter source for the star and a dimmer one for the planet. Acquiring spectral information about the secondary source is difficult because the two images have a substantial overlap. This limitation is solved by leveraging a structured measurement based on spatial-mode demultiplexing, where light is first sorted in its Hermite–Gaussian components in the transverse field then measured by photon detection. This allows us to effectively decouple the photons coming from the two sources. An application is suggested to enhance the exoplanets’ atmosphere spectroscopy. A number of experiments of super-resolution imaging based on spatial demultiplexing have been conducted in the past few years, with promising results. Here, for the first time to the best of our knowledge, we extend this concept to the domain of spectroscopy.We demonstrate the spectroscopy of incoherent light with subdiffraction resolution. In a proof-of-principle experiment, we analyze the spectrum of a pair of incoherent pointlike sources whose separation is below the diffraction limit. The two sources mimic a planetary system, with a brighter source for the star and a dimmer one for the planet. Acquiring spectral information about the secondary source is difficult because the two images have a substantial overlap. This limitation is solved by leveraging a structured measurement based on spatial-mode demultiplexing, where light is first sorted in its Hermite–Gaussian components in the transverse field then measured by photon detection. This allows us to effectively decouple the photons coming from the two sources. An application is suggested to enhance the exoplanets’ atmosphere spectroscopy. A number of experiments of super-resolution imaging based on spatial demultiplexing have been conducted in the past few years, with promising results. Here, for the first time to the best of our knowledge, we extend this concept to the domain of spectroscopy..
Photonics Research
- Publication Date: Mar. 21, 2025
- Vol. 13, Issue 4, 865 (2025)
Tracking and manipulating ultrafast photocarrier dynamics in 3D Dirac semimetal Cd3As2 by chemical doping
Peng Suo, Wenjie Zhang, Yunkun Yang, Long Geng... and Guohong Ma|Show fewer author(s)
Element doping can break the crystal symmetry and realize the topological phase transition in quantum materials, which enables the precise modulation of energy band structure and microscopic dynamical interaction. Herein, we have studied the ultrafast photocarrier dynamics in Zn-doped 3D topological Dirac semimetal Cd3As2 utilizing time-resolved optical pump-terahertz probe spectroscopy. Comparing to the pristine Cd3As2, we found that the relaxation time of the lightly doped alloy is slightly shorter, while that of the heavily doped alloy exhibits a significant prolongation. Pump-fluence- and temperature-dependent transient terahertz spectroscopy indicated that in pristine and lightly doped samples within nontrivial semimetal phase, the photocarrier dynamics are dominated by the cooling of Dirac fermions. In heavily doped alloy, however, the observed longer relaxation process can be attributed to interband electron-hole recombination, which is a result of doping-induced transition into a trivial semiconductor phase. Our investigation highlights that Zn-doping is an effective and flexible scheme for engineering the electronic structure and transient carrier relaxation dynamics in Cd3As2, and offers a control knob for functional switching between diverse optoelectronic devices within the realm of practical applications.Element doping can break the crystal symmetry and realize the topological phase transition in quantum materials, which enables the precise modulation of energy band structure and microscopic dynamical interaction. Herein, we have studied the ultrafast photocarrier dynamics in Zn-doped 3D topological Dirac semimetal
Photonics Research
- Publication Date: Apr. 01, 2025
- Vol. 13, Issue 4, 1028 (2025)
Surface Optics and Plasmonics
Broadband transmission-reflection-integrated metasurface capable of arbitrarily polarized wavefront manipulation in full space
Zuntian Chu, Xinqi Cai, Jie Yang, Tiefu Li... and Shaobo Qu|Show fewer author(s)
In modern science and technology, on-demand control of the polarization and wavefront of electromagnetic (EM) waves is crucial for compact opto-electronic systems. Metasurfaces composed of subwavelength array structures inject infinite vitality to shape this fantastic concept, which has fundamentally changed the way humans engineer matter–wave interactions. However, achieving full-space arbitrarily polarized beams with independent wavefronts in broadband on a single metasurface aperture still remains challenging. Herein, the authors propose a generic method for broadband transmission-reflection-integrated wavefronts shaping with multichannel arbitrary polarization regulation from 8 to 16 GHz, which is based on the chirality effect of full-space non-interleaved tetrameric meta-molecules. Through superimposing eigen-polarization responses of the two kinds of enantiomers, the possibility for high-efficiency evolution of several typical polarization states with specific wavefronts is demonstrated. As proofs-of-concept, the feasibility of our methodology is validated via implementing miscellaneous functionalities, including circularly polarized (CP) beam splitting, linearly polarized (LP) vortex beams generation, and CP and LP multifoci. Meanwhile, numerous simulated and experimental results are in excellent agreement with the theoretical predictions. Encouragingly, this proposed approach imaginatively merges broadband polarization and phase control into one single full-space and shared-aperture EM device, which can extremely enhance the functional richness and information capacity in advanced integrated systems.In modern science and technology, on-demand control of the polarization and wavefront of electromagnetic (EM) waves is crucial for compact opto-electronic systems. Metasurfaces composed of subwavelength array structures inject infinite vitality to shape this fantastic concept, which has fundamentally changed the way humans engineer matter–wave interactions. However, achieving full-space arbitrarily polarized beams with independent wavefronts in broadband on a single metasurface aperture still remains challenging. Herein, the authors propose a generic method for broadband transmission-reflection-integrated wavefronts shaping with multichannel arbitrary polarization regulation from 8 to 16 GHz, which is based on the chirality effect of full-space non-interleaved tetrameric meta-molecules. Through superimposing eigen-polarization responses of the two kinds of enantiomers, the possibility for high-efficiency evolution of several typical polarization states with specific wavefronts is demonstrated. As proofs-of-concept, the feasibility of our methodology is validated via implementing miscellaneous functionalities, including circularly polarized (CP) beam splitting, linearly polarized (LP) vortex beams generation, and CP and LP multifoci. Meanwhile, numerous simulated and experimental results are in excellent agreement with the theoretical predictions. Encouragingly, this proposed approach imaginatively merges broadband polarization and phase control into one single full-space and shared-aperture EM device, which can extremely enhance the functional richness and information capacity in advanced integrated systems..
Photonics Research
- Publication Date: Mar. 11, 2025
- Vol. 13, Issue 4, 798 (2025)
Reusable high-Q plasmonic metasurface
Qianwen Jia, Junhong Deng, Anwen Jiang, Guoxia Yang... and Jinwei Shi|Show fewer author(s)
Metallic nanostructures supporting surface plasmons are crucial for various ultrathin photonic devices. However, these applications are often limited by inherent metallic losses. Significant efforts have been made to achieve high quality-factor (Q-factor) resonances in plasmonic metasurfaces, particularly through surface lattice resonances (SLRs) and bound states in the continuum (BICs). Despite these advances, a direct comparison between these two mechanisms remains unexplored. Here, we report a reusable plasmonic metasurface that supports multiple high-Q resonances by leveraging hybrid plasmonic–photonic modes. By systematically tuning the lattice constant and dielectric cladding thickness, we achieve substantial Q-factor enhancements of both SLRs and BICs in a monolithic device with a small footprint of 200 μm×200 μm by using an incoherent light source. A direct comparison between these two resonances is also discussed. This high-Q performance holds significant promise for applications in sensing, lasing, and nonlinear and quantum optics, paving the way for the development of next-generation nanophotonic devices.Metallic nanostructures supporting surface plasmons are crucial for various ultrathin photonic devices. However, these applications are often limited by inherent metallic losses. Significant efforts have been made to achieve high quality-factor (
Photonics Research
- Publication Date: Apr. 01, 2025
- Vol. 13, Issue 4, 1010 (2025)
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