Continuous-variable quantum key distribution (CV-QKD) suffers from significant secret key rate (SKR) limitations in long-haul transmission. Existing hardware-oriented capacity boosting approaches are hindered by prohibit...Continuous-variable quantum key distribution (CV-QKD) suffers from significant secret key rate (SKR) limitations in long-haul transmission. Existing hardware-oriented capacity boosting approaches are hindered by prohibitive costs and intricate system architectures. To address these challenges, this paper proposes a time-domain unitary precoding scheme to enhance the SKR by making full use of the non-flat noise frequency spectrum inherent to practical CV-QKD systems. This paper derives an analytical expression for the optimal precoder when only excess or electronic noise is colored and employs the Riemann Conjugate Gradient (RCG) algorithm for iterative optimization when both types of noise are colored. Numerical simulations demonstrate that, for a 40 km transmission link with both colored excess noise and electronic noise, the optimized scheme attains a 1.07 to 5.6 fold SKR improvement compared to conventional CV-QKD systems.
Digital in-line holographic microscopy enables label-free tracking and metrology, but achieving nanometric sub-pixel displacement accuracy over a wide capture range remains challenging. Frequency-domain registration base...Digital in-line holographic microscopy enables label-free tracking and metrology, but achieving nanometric sub-pixel displacement accuracy over a wide capture range remains challenging. Frequency-domain registration based on the discrete Fourier transform (DFT) is globally stable and tolerant to large shifts, yet it suffers from sub-pixel quantization and interpolation artifacts that limit precision near zero displacement. In contrast, spatial-gradient refinement such as Lucas-Kanade (LK) can reach very high sub-pixel accuracy, but it is strongly initialization-limited and prone to divergence outside a narrow convergence basin. Here, we propose a Hybrid Spectral-Spatial Domain (HSSD) framework that resolves this trade-off by combining the global robustness of a DFT-based coarse estimator with LK refinement of the residual motion. We validate HSSD using numerical simulations and experiments in a transmission in-line holographic imaging system, achieving nanometric-precision displacement measurement and stable tracking across a wide range of displacements and defocusing conditions. This hybrid strategy enables reliable nanometric localization in regimes where standalone DFT or LK methods either fail to converge or saturate in accuracy.
This paper presents a metasurface with dual-band extrinsic chirality based on a metal-insulator-metal (MIM) structure. The metasurface utilizes mirror-symmetric split-ring resonators as fundamental building blocks. Under...This paper presents a metasurface with dual-band extrinsic chirality based on a metal-insulator-metal (MIM) structure. The metasurface utilizes mirror-symmetric split-ring resonators as fundamental building blocks. Under oblique microwave incidence, the in-plane mirror symmetry is effectively broken, inducing chiral electromagnetic resonance modes at two distinct frequencies. The selective coupling and suppression of left- and right-handed circularly polarized waves by the meta-atoms generate strong circular dichroism with opposite signs at the two frequencies. Concurrently, the different sensitivities of the resonant modes to incident angle variations result in mirror-symmetric frequency shifts for the two cross-polarization components within the bands, enabling flexible angular dispersion control. Under TM-polarized wave incidence, varying the incident and azimuth angles can excite significant phase dispersion, leading to rich polarization state evolution over the entire Poincaré sphere across the entire operating frequency band. By introducing the "incident angle" as a control dimension, this work provides a new, to the best of our knowledge, approach for multi-band, reconfigurable chiral responses and dynamic polarization manipulation, holding significant promise for applications in electromagnetic communication, polarization imaging, and related fields.
In this Letter, we report on the demonstration of InGaN/AlGaN nanowire red light-emitting diodes, which exhibit high thermal robustness under extreme operating conditions. The devices emit at a wavelength of ~650 nm and...In this Letter, we report on the demonstration of InGaN/AlGaN nanowire red light-emitting diodes, which exhibit high thermal robustness under extreme operating conditions. The devices emit at a wavelength of ~650 nm and maintain stable red electroluminescence over injection currents from 10 to 1000 mA. Temperature-dependent electroluminescence characterization reveals sustained emission from 25 °C to ~950 °C under ramped conditions with a minimal peak wavelength shift of ~3-5 nm and moderate spectral broadening of ~10 nm. The emission linewidth remains broad, with a full width at half maximum of ~94 nm across the entire temperature range. These results establish III-nitride nanowire LEDs as a robust platform for high-temperature red emission, with implications for optoelectronic systems operating in harsh environments, including aerospace, high-temperature industrial processes, and advanced sensing.
We experimentally demonstrate transitions between stably mode-locked and noise-like pulse states in a ytterbium-doped fiber laser controlled by adjusting the level of intracavity spectral filtering. In both regimes, Kerr...We experimentally demonstrate transitions between stably mode-locked and noise-like pulse states in a ytterbium-doped fiber laser controlled by adjusting the level of intracavity spectral filtering. In both regimes, Kerr spatial self-cleaning provides high-quality output beams. By using cavities with different lengths of graded-index fiber, we show that, in the mode-locked regime, a proper balance between chromatic and modal dispersion maximizes pulse compressibility. We compress 2.1-kW, 6.7-ps pulses down to 170 fs using an external grating pair, in good agreement with numerical simulations.
Self-starting operation is highly desirable for practical Kerr-lens mode-locked oscillators, but it is difficult to combine with high-energy few-cycle performance. Here, we demonstrate a self-starting dispersion-managed...Self-starting operation is highly desirable for practical Kerr-lens mode-locked oscillators, but it is difficult to combine with high-energy few-cycle performance. Here, we demonstrate a self-starting dispersion-managed Kerr-lens mode-locked Cr:ZnS oscillator at 2.3 µm and 25.6 MHz using a single-walled carbon nanotube (SWCNT) saturable absorber. The SWCNT enables reliable self-starting while preserving Kerr-lens-driven spectral broadening, yielding 30-fs pulses. Dispersion-managed operation reduces nonlinear phase accumulation in the gain crystal and increases the maximum pulse energy to above 20 nJ. After external dispersion compensation, the oscillator delivers peak powers of∼0.7 MW. The output further drives octave-spanning spectral broadening in rutile, establishing a practical self-starting Cr:ZnS platform toward mid-infrared laser science.
Structured light fields exploit spin and orbital angular momentum for precision manipulation, advanced imaging, and high-capacity communication. We develop a paraxial modal framework that couples the circular polarizatio...Structured light fields exploit spin and orbital angular momentum for precision manipulation, advanced imaging, and high-capacity communication. We develop a paraxial modal framework that couples the circular polarization basis, a spin-1/2 representation of su(2), with finite-dimensional Laguerre-Gaussian modal subspaces at fixed order that carry spin- representations. The Clebsch-Gordan decomposition of our product representation yields paraxial total angular momentum fields, and the action of an SU(2) rotation on the lowest-weight state of each subspace defines total angular momentum coherent state fields. A single complex parameter controls polarization and spatial structure jointly. Our fields propagate self-similarly, preserving their transverse polarization and spatial structure up to a scale factor. We present a proof-of-principle experiment to support the feasibility of our construction.
Parametrically driven solitons are self-trapped modes in various physical settings, including optics, magnetics, etc. So far, the analysis has been focused on the existence, stability, and dynamics of such solitons in sy...Parametrically driven solitons are self-trapped modes in various physical settings, including optics, magnetics, etc. So far, the analysis has been focused on the existence, stability, and dynamics of such solitons in systems including the second-order group-velocity dispersion (GVD), linear loss, parametric gain, and cubic nonlinearity. Here, we report the existence of quiescent parametrically driven pure-quartic solitons (PDPQSs) in the full system and moving PDPQSs in the absence of losses. A systematic analysis reveals stability domains for the solitons in the system's parameter space. Evolution of unstable states is explored, too, and it is demonstrated that collisions between traveling stable PDPQSs are elastic.
Machine learning (ML) has emerged as a promising technique for nonlinear equalization in coherent optical communication systems. However, conventional ML-based equalization schemes typically rely on fixed network archite...Machine learning (ML) has emerged as a promising technique for nonlinear equalization in coherent optical communication systems. However, conventional ML-based equalization schemes typically rely on fixed network architectures and parameters, limiting the adaptability to dynamic link states such as varying launch powers and transmission distances. In this Letter, we propose a pre-monitoring-assisted deep cascaded network (DCN) for nonlinear equalization. A lightweight convolutional neural network (CNN) performs pre-monitoring by analyzing the received signal spectrum to identify link states, thereby selecting the optimal deep neural network (DNN) model for nonlinear equalization. Experimental demonstrations in a 28-GBaud PDM-16QAM system show that, at the optimum launch power for 250 km transmission, the proposed scheme achieves a Q-factor gain of 2.01 dB over linear equalization, with a computational complexity of 2885 real multiplications per symbol (RMpS).
We demonstrate a miniature laser based on a cylindrical whispering-gallery-mode (WGM) microresonator made of erbium-doped tellurite glass. The laser is excited by a widely available broadband 976 nm laser diode and opera...We demonstrate a miniature laser based on a cylindrical whispering-gallery-mode (WGM) microresonator made of erbium-doped tellurite glass. The laser is excited by a widely available broadband 976 nm laser diode and operates in the telecommunication C- and L-band spectral regions. Spatial confinement for the axially propagating modes was achieved by introducing effective radius variations (ERVs). We show wavelength tuning and band switching by selective excitation of different axial modes. The laser exhibits narrow-linewidth operation, confirmed experimentally. The results demonstrate the potential of erbium-doped cylindrical microresonators as compact, tunable, and narrow-band laser sources for telecommunication and integrated photonic applications.
A lab-in-a-fiber sensor platform is demonstrated, enabling simultaneous optical analysis and controlled microfluidic transport in a single monolithic device. It consists of a high-aspect-ratio flat fiber (HARFF) that int...A lab-in-a-fiber sensor platform is demonstrated, enabling simultaneous optical analysis and controlled microfluidic transport in a single monolithic device. It consists of a high-aspect-ratio flat fiber (HARFF) that integrates a mechanically compliant elliptical fused silica capillary and a Ge-doped single-mode waveguide. The waveguide, partially exposed to the capillary, provides evanescent field interaction with analytes introduced into the central microfluidic channel. The high-aspect-ratio microfluidic channel confines side wall effects, producing a flattened laminar flow that supports stable real-time imaging. Alongside particle-flow monitoring, the device exhibits a tunable refractive-index sensitivity. Through in-plane flexure, a more than three-fold sensitivity enhancement was demonstrated at a 50 mm bending radius over a straight fiber. This hybrid fiber sensor design represents cost-effective production of a compact and versatile platform for lab-in-fiber applications, combining optical interrogation and microfluidic functionality.
The demand for multifunctional optoelectronics is rapidly growing, driven by advances in information technology. The low-dimensional homojunctions exhibit ease in realizing direct current (DC) electro-driven light emissi...The demand for multifunctional optoelectronics is rapidly growing, driven by advances in information technology. The low-dimensional homojunctions exhibit ease in realizing direct current (DC) electro-driven light emission and effective self-powered photodetection capability induced by the built-in electric field. Here, a lateral InSe homojunction was fabricated by integrating two-dimensional CrOCl on InSe to induce interfacial localized p-type doping. The device exhibited DC electroluminescence (EL) with a maximum external quantum efficiency (EQE) value that could reach 60 times higher than its intrinsic counterpart. Benefiting from the built-in electric field in the homojunction region, the device possessed a high photoresponsivity of 96.84 mA/W, a fast temporal response of 6 (rise) and 62 (decay) μs, as well as a remarkable detectivity (D) of 1.028 × 10 Jones of 450 nm. This work manifests a novel approach to fabricating a lateral homojunction and reveals its potential application in a next-generation optoelectronic interconnect system.
We present an erratum to our Letter [Opt. Lett.50, 5214 (2025)10.1364/OL.566758] correcting two typographical errors: (1) in the expression for following Eq. (2), and (2) in the expression for following Eq. (3). All th...We present an erratum to our Letter [Opt. Lett.50, 5214 (2025)10.1364/OL.566758] correcting two typographical errors: (1) in the expression for following Eq. (2), and (2) in the expression for following Eq. (3). All the simulations in the original Letter were performed using the correct expressions for and , and therefore this correction does not affect the results and conclusions of the original Letter.
This paper presents a laser interferometric method based on 3D-EFA for high-precision displacement and vibration measurement. Using three DFB lasers (1540.600, 1549.360, and 1558.160 nm) and a dual-cavity EFPI sensor, ra...This paper presents a laser interferometric method based on 3D-EFA for high-precision displacement and vibration measurement. Using three DFB lasers (1540.600, 1549.360, and 1558.160 nm) and a dual-cavity EFPI sensor, rapid displacement and remote vibration measurement were demonstrated via a PZT driven by a signal generator. The 3D-EFA algorithm enables stable demodulation with <0.3% error while maintaining robust performance over extended standoff distances, significantly improving speed and accuracy.
In this Letter, we propose a torsion sensor based on a serially cascaded left- and right-handed helical sampled fiber Bragg grating pair (L&R-HSFBG-Pair) inscribed in a single-mode fiber (SMF) using point-by-point (PbP)...In this Letter, we propose a torsion sensor based on a serially cascaded left- and right-handed helical sampled fiber Bragg grating pair (L&R-HSFBG-Pair) inscribed in a single-mode fiber (SMF) using point-by-point (PbP) femtosecond laser technique. Owing to their opposite response trends under torsion, the sensor can discriminate the twist direction and enable differential interrogation. The twist rate is quantified by monitoring the reflected peak power at the Bragg wavelength, which shows negligible dependence on temperature and axial strain within the tested ranges, thereby avoiding the need for additional temperature-compensation components. Differential interrogation of the two reflected peaks further improves the effective torsion sensitivity while suppressing common-mode fluctuations in light-source power. This sensor exhibits a torsion sensitivity of 0.25 dB/(rad·m), which corresponds to 0.071/(rad·m) after normalization. The proposed sensor therefore shows strong potential for torsion monitoring in harsh environments subject to temperature fluctuations and electromagnetic interference.
The Ince-Gaussian modes form a complete set of solutions to the paraxial wave equation parametrized by an ellipticity parameter , enabling a continuous transition between Laguerre- and Hermite-Gaussian modes. While each...The Ince-Gaussian modes form a complete set of solutions to the paraxial wave equation parametrized by an ellipticity parameter , enabling a continuous transition between Laguerre- and Hermite-Gaussian modes. While each fixed defines an orthogonal basis, modes associated with different ellipticities are not mutually orthogonal, and no explicit transformation between such bases has been reported. Here, we derive the first explicit finite analytical expression to transform between Ince-Gaussian bases of arbitrary ellipticity, enabling direct and experimentally accessible mapping between non-orthogonal structured-light representations. We further demonstrate an experimental implementation using spatial light modulators to perform ellipticity-resolved modal decomposition. This framework introduces ellipticity as a controllable degree of freedom for structured light engineering, enabling new strategies for mode conversion, encoding, and high-dimensional optical information processing.
We demonstrate a 3.2 µm mid-infrared source delivering 30 µJ, single-cycle pulses via two-stage bulk post-compression of a 10 W four-cycle OPCPA. By optimizing a tandem configuration of BaF and Si, we achieved a compress...We demonstrate a 3.2 µm mid-infrared source delivering 30 µJ, single-cycle pulses via two-stage bulk post-compression of a 10 W four-cycle OPCPA. By optimizing a tandem configuration of BaF and Si, we achieved a compressed pulse duration of 11 fs with a CEP stability of 145 mrad RMS. The output exhibited high spatio-spectral uniformity with small residual spatial and angular chirp. The reliability and long-term stability of the system are tested. Additionally, high-order harmonics were generated in ZnO with locked CEP. The demonstrated performance is ideal for strong-field and attosecond-science applications.
Improving the integration density of photonic integrated circuits is essential for reducing chip cost, and waveguide bends are a critical component that governs routing density and device compactness. However, achieving...Improving the integration density of photonic integrated circuits is essential for reducing chip cost, and waveguide bends are a critical component that governs routing density and device compactness. However, achieving compact waveguide bends is particularly challenging in the short-wave mid-infrared band, where longer wavelengths weaken optical confinement and increase radiation loss, imposing strict limits on the minimum bending radius. Here, we propose and experimentally demonstrate a compact waveguide bend for the short-wave mid-infrared wavelength band by implementing a Mikaelian lens using subwavelength engineering. The aberration-free property of the Mikaelian lens enables efficient optical connection between parallel ports with flexible longitudinal separation within a device footprint of 19 × 16 μm². The fabricated device achieves a bending loss of 0.5 dB and crosstalk of -17 dB. This work demonstrates a promising approach to achieving flexible, dense routing in photonic integrated circuits for short-wave mid-infrared or even longer-wavelength applications.
Super multi-view (SMV) display offers a promising solution for three-dimensional (3D) displays by projecting dense views directly into the single pupil. However, conventional SMV architectures face a trade-off between vi...Super multi-view (SMV) display offers a promising solution for three-dimensional (3D) displays by projecting dense views directly into the single pupil. However, conventional SMV architectures face a trade-off between view density and spatial resolution for individual views. Here, we propose a view density enhancement method based on a polarization-multiplexed metasurface. The metasurface contains two sets of cylindrical lens array phase profiles with opposite lateral focal shifts under orthogonal polarization states. A proof-of-concept prototype was fabricated and characterized, and the experimental results demonstrate that the proposed device generates two groups of interleaved views and reduces the angular separation between adjacent views from 6° to 3°, thereby doubling the view density without compromising the spatial resolution of individual views. This work offers a promising strategy and compact route for view-density enhancement in advanced SMV displays.
Conventional optical microscopes are constrained by discrete magnification settings, limiting continuous multi-scale observation. Although liquid lenses enable continuous zoom, their practical performance is often compro...Conventional optical microscopes are constrained by discrete magnification settings, limiting continuous multi-scale observation. Although liquid lenses enable continuous zoom, their practical performance is often compromised by dynamic aberrations and electrowetting-induced oscillations. Here, we propose a deep learning-enabled computational adaptive-optics (AO) framework for fast continuous zoom microscopy. Our physics-inspired network directly estimates the point spread function (PSF) from degraded images by leveraging complementary frequency-domain cues and spatial gradient information. By coupling sliding window self-attention with PSF-guided dynamic filtering, the model achieves accurate image restoration across zoom states. In addition, we introduce a degradation model that simulates electrowetting liquid-surface oscillations together with realistic imaging degradations. Experiments validate that this computational AO approach accelerates continuous zoom imaging while remaining robust to vignetting-induced non-uniform illumination, thereby enabling fast, high-quality multi-scale observation in continuous zoom microscopy.