Electrically reconfigurable photonics based on optical phase change materials (PCMs) has attracted surging interest recently, with broad potential applications ranging from analog computing to optical camouflage. PCM swi...Electrically reconfigurable photonics based on optical phase change materials (PCMs) has attracted surging interest recently, with broad potential applications ranging from analog computing to optical camouflage. PCM switching in these devices is customarily implemented using resistive micro-heaters. These electrically conductive micro-heaters, however, cause significant optical losses due to free carrier absorption. In this paper, we present a design concept that overcomes this limitation without compromising the electrical performance of the micro-heaters. Using doped Si heaters as an example, we show that such parasitic losses can be suppressed by engineering the optical mode to minimize the optical field overlap with the lossy doped region. An active optical meta-grating design was proposed based on the concept, which achieves 2 phase tuning range near 1.53 μm wavelength with only 10 nm thick SbS while maintaining over 85% optical efficiency.
We experimentally demonstrate a signal-reference modal correlation method for retrieving structured optical modal signatures after propagation through a scattering medium. Hermite-Gaussian and Laguerre-Gaussian modes tra...We experimentally demonstrate a signal-reference modal correlation method for retrieving structured optical modal signatures after propagation through a scattering medium. Hermite-Gaussian and Laguerre-Gaussian modes transmitted through the medium produce randomized speckle patterns in direct intensity measurements, obscuring their spatial structure. By computing the spatial cross-correlation between each signal speckle and a single fixed Gaussian reference, distinct modal morphology emerges in the central correlation peak. Cartesian parity symmetry is recovered for Hermite-Gaussian modes, while charge-dependent radial scaling is resolved for Laguerre-Gaussian modes. The approach requires no transmission-matrix calibration, wavefront shaping, or machine-learning-assisted reconstruction, providing a compact and experimentally accessible framework for structured-light discrimination in complex scattering environments.
We demonstrate an ultra-narrow-linewidth laser by locking a commercial external-cavity diode laser (ECDL) to a cascaded, all-fiber reference. To circumvent the challenge of directly locking broad-linewidth sources (>100 ...We demonstrate an ultra-narrow-linewidth laser by locking a commercial external-cavity diode laser (ECDL) to a cascaded, all-fiber reference. To circumvent the challenge of directly locking broad-linewidth sources (>100 kHz) to a high-finesse fiber reference, we employ a two-stage scheme, where a fiber ring resonator provides initial pre-stabilization, followed by a fiber delay line interferometer for further spectral purification. The stabilized laser achieves a 100-ms 1/ integrated linewidth of 28 Hz, a fundamental linewidth of 0.1 Hz, and frequency-noise suppression exceeding 80 dB at 30 Hz-1 kHz offset frequencies. Moreover, the scheme remains effective across the ECDL tuning range of 1520-1580 nm, hence offering both ultra-low phase noise and broad wavelength agility for precision metrology applications.
Designing freeform optics for extended light sources remains a challenge in illumination design, since conventional design methods for zero-étendue sources are difficult to extend to general, finite-étendue sources. As a...Designing freeform optics for extended light sources remains a challenge in illumination design, since conventional design methods for zero-étendue sources are difficult to extend to general, finite-étendue sources. As an alternative to these conventional methods, this work introduces a framework for direct prediction of zero-étendue freeform illumination surfaces. A multi-stage training strategy is presented for a deep neural network enabling near-instant prediction of smooth freeform geometries for point sources and random target irradiance distributions of varying sizes. The predicted designs achieve high irradiance fidelity and serve as effective initialization for differentiable fine-tuning, requiring only a couple of optimization iterations to reach ultra-precise irradiance control. This represents the first, to the best of our knowledge, deep learning framework for nonimaging freeform illumination design with zero-étendue sources. While this work focuses on zero-étendue sources, the multi-configuration capability of the framework provides a fundamental base that can be extended to eventually capture the full spatial and angular emission characteristics of finite-étendue sources.
We demonstrate reproducible asymmetric directional couplers in gallium-lanthanum-sulfide (GLS) chalcogenide glass, using ultrafast laser inscription (ULI). This enables on-chip high-contrast nulling interferometry in the...We demonstrate reproducible asymmetric directional couplers in gallium-lanthanum-sulfide (GLS) chalcogenide glass, using ultrafast laser inscription (ULI). This enables on-chip high-contrast nulling interferometry in the mid-infrared, specifically aimed at detecting giant exoplanets in the astronomical L band (3.5-4.0 μm). By leveraging a classical two-telescope integrated optics beam combination scheme and conducting characterization in a laboratory environment, we demonstrate an extinction ratio of ∼10 across 3.65-3.85 μm.
Fano resonances in thin-film optics exhibit strong angular dispersion, which severely degrades the factors and significantly distorts the lineshapes. In this Letter, we theoretically demonstrate an angle-dispersion-free...Fano resonances in thin-film optics exhibit strong angular dispersion, which severely degrades the factors and significantly distorts the lineshapes. In this Letter, we theoretically demonstrate an angle-dispersion-free Fano resonance in a heterostructure composed of a plasmonic layer and two one-dimensional photonic hypercrystals. This fascinating property of the Fano resonance originates from the interference between an angle-dispersion-free continuum and an angle-dispersion-free optical Tamm state. As the incident angle increases from 0 to 80 degrees, the Fano dip exhibits an extremely small wavelength shift of less than 0.1%, while its factor remains highly stable. Our work breaks the angular dispersion limit of Fano resonances in thin-film optics.
Over the past decade, the application of liquid crystal (LC) in switchable smart windows (SW) has emerged as a research hotspot. However, LC alignment technologies and their associated fabrication processes have constrai...Over the past decade, the application of liquid crystal (LC) in switchable smart windows (SW) has emerged as a research hotspot. However, LC alignment technologies and their associated fabrication processes have constrained the further practical application of SW. This study proposes an alignment-free SW based on a negative dielectric LC (NDLC) system doped with S811 and DTAB, which achieves the synergistic effect between ionic turbulence and the focal conic state. Characterized by a simple preparation process and convenient operation, this smart window holds promising application prospects in architecture-related fields.
Integrated nonlinear microring resonators are promising sources of bright twin-beams exhibiting intensity difference squeezing. To take advantage of the noise reduction of these quantum states, many applications require...Integrated nonlinear microring resonators are promising sources of bright twin-beams exhibiting intensity difference squeezing. To take advantage of the noise reduction of these quantum states, many applications require high squeezing levels. However, the attainable on-chip squeezing is constrained by the ratio of intrinsic to coupling loss, which is strongly related to design and fabrication limits. Here, we demonstrate a silicon nitride microring resonator engineered to enable a set of periodic strongly overcoupled resonances from which the estimated on-chip intensity difference squeezing is 11.8 dB, exceptionally high for an integrated device. Due to significant setup loss, we directly measure 1.4±0.2 dB of squeezing, corresponding to an on-chip level of 9.2±5.1 dB. In addition, the new, to the best of our knowledge, design inherently suppresses mode competition in the modes surrounding the twin-beams, enabling a constant high squeezing level up to moderate powers. These results represent a significant step toward the miniaturization of integrated devices whose performance benefits from surpassing the quantum noise limit using squeezed states, with particular relevance to sensing applications.
A novel broadband, high-resolution spectroradiometer based on a virtually imaged phased array (VIPA) has been developed to meet the stringent requirements for high-precision vertical profiles of key atmospheric constitue...A novel broadband, high-resolution spectroradiometer based on a virtually imaged phased array (VIPA) has been developed to meet the stringent requirements for high-precision vertical profiles of key atmospheric constituents. The instrument operates within the spectral range of 7535-7680 cm, achieving a spectral resolution of 0.023 cm (690 MHz) with an integration time as short as 400 ms. Using this system, high-resolution atmospheric transmittance spectra in the 7535-7680 cm band were successfully measured, and the vertical profile of water vapor was retrieved using the optimal estimation method (OEM). The results demonstrate that the novel VIPA-based spectroradiometer enables rapid acquisition of high-resolution atmospheric transmittance spectra over a broad spectral range, providing a robust and effective new approach for remote sensing of key atmospheric constituents. To the best of our knowledge, this represents the first successful application of a VIPA-based spectroradiometer for retrieving vertical profiles of atmospheric constituents.
Simultaneous measurement of dispersed and continuous phases in multiphase flows remains a fundamental challenge. This Letter proposes holographic background-oriented schlieren (HoloBOS), and it enables numerical refocusi...Simultaneous measurement of dispersed and continuous phases in multiphase flows remains a fundamental challenge. This Letter proposes holographic background-oriented schlieren (HoloBOS), and it enables numerical refocusing of both the background pattern and dispersed-phase particles from a single acquisition, thereby allowing simultaneous characterization of both phases. The method is demonstrated in a gas flame experiment with an effective distance of 45 mm and is further applied to a multiphase propellant combustion plume to characterize dispersed agglomerates and flow structures. The results support the feasibility of HoloBOS for the simultaneous extraction of particle morphology, size, and three-dimensional position, as well as the line-of-sight integral of the refractive-index gradient in the continuous phase, indicating its potential as a practical tool for complex multiphase diagnostics.
New laser technologies reaching multi-kilowatt average powers, with the intrinsic capacity to deliver energetic pulses, are required for upcoming high-profile applications of intense lasers. We demonstrate that a diode-p...New laser technologies reaching multi-kilowatt average powers, with the intrinsic capacity to deliver energetic pulses, are required for upcoming high-profile applications of intense lasers. We demonstrate that a diode-pumped, rotating multi-disk Yb:YAG technology, coupled with direct face-cooling by heavy water, reaches an average power of 2 kW in an 8-pass configuration, at a wavelength of 1030 nm in continuous wave mode, with a slope efficiency of 33%, an M of 2.4 at highest power, and a pointing stability of 2.5 µrad rms in spite of the disk rotation. The extractable energy is 4.3 J. This face-cooled rotating multi-disk amplifier (FCRMDA) technology paves the way to increase average powers for joule class picosecond lasers, with a horizon at the 10-kW level.
Mitigating the impact of pointing jitter is a prerequisite for achieving high-precision Dispersed Fringe Sensing (DFS) in dynamic environments. This Letter proposes a tilt-robust phase decoupled reconstruction (PDR) meth...Mitigating the impact of pointing jitter is a prerequisite for achieving high-precision Dispersed Fringe Sensing (DFS) in dynamic environments. This Letter proposes a tilt-robust phase decoupled reconstruction (PDR) method that utilizes the strict vanishing of tip/tilt-induced phase modulation at the spatial carrier-frequency peak. Leveraging this property, the PDR method extracts the tilt-immune piston phase at the carrier peak and employs multi-wavelength least-squares unwrapping to retrieve the absolute piston error. Both numerical simulations and experiments confirm the method's excellent tilt robustness. Specifically, an experimental piston retrieval precision of 0.034 μm RMS is achieved under continuous sinusoidal pointing jitter, demonstrating the method's capability for high-precision co-phasing in future synthetic aperture telescopes.
We report a mechanism-driven no-core fiber (NCF) glucose sensor, which not only features a polydopamine/polyethylenimine (PDA/PEI) coating that enhances the evanescent field, but also enables real-time monitoring of the...We report a mechanism-driven no-core fiber (NCF) glucose sensor, which not only features a polydopamine/polyethylenimine (PDA/PEI) coating that enhances the evanescent field, but also enables real-time monitoring of the bio-interface assembly. For the first time, to the best of our knowledge, the dynamic PDA/PEI deposition and the successive glucose oxidase (GOx) immobilization were tracked by the NCF itself, thus providing unprecedented insight into the formation kinetics of the sensing layer. The physicochemical characterization reveals that the engineered PDA/PEI composite exhibits a high refractive index (RI) of ∼1.55 and a low extinction coefficient of ∼0.02 in the near-infrared region, which significantly enhances the evanescent field and thus RI sensitivity of the sensor by ∼19.8%. A peak sensitivity of ∼96 pm/mM was achieved at the optimized condition (PDA:PEI = 2:0.5, 6 h deposition), with a linear range of 1-12 mM, a limit of detection (LOD) of 0.19 mM, and a response time of ∼22 s. The sensor also demonstrated good selectivity toward glucose in a representative biomass hydrolysis system and showed potential applicability in pretreated hydrolysate samples. This work presents a high-performance fiber-optic glucose sensor and demonstrates the utility of real-time monitoring for understanding bio-interface assembly in optical biosensors.
We predict that dispersive shock waves can be observed in multimode fibers with a parabolic index profile despite competing with geometric parametric instability. Spatial self-imaging forces these shock waves to radiate...We predict that dispersive shock waves can be observed in multimode fibers with a parabolic index profile despite competing with geometric parametric instability. Spatial self-imaging forces these shock waves to radiate at multiple resonant frequencies even in the absence of relevant higher-order dispersion. A simple phase-matching rule derived from a reduced model accurately describes such resonances in agreement with a full 1 + 3D model. This allows to interpret spectral reshaping of intense pulses occurring in the normal dispersion regime.
Light polarization states are the intrinsic properties of light and are widely exploited in fields such as remote sensing, computing, and medical imaging. Conventional photoelectric sensors used for polarization detectio...Light polarization states are the intrinsic properties of light and are widely exploited in fields such as remote sensing, computing, and medical imaging. Conventional photoelectric sensors used for polarization detection are fundamentally constrained by the wavelength-dependent bandgap of their constituent materials, and therefore hinder their ability to meet the practical demands of broadband high-contrast polarization detection. To address this limitation, we develop a time-division photoacoustic sensing-based polarization detection (PSPD) scheme that exploits the polarization-dependent photoacoustic response of an optically anisotropic absorbing transducer at a wide spectral range, enabling broadband polarization detection from the visible to the second near-infrared window (NIR-II) with high polarization contrast. Moreover, leveraging the depth-resolved nature of the photoacoustic effect, we show that the z-axis extension of PSPD can facilitate fast multiplexed polarization readout toward polarization imaging. The proposed PSPD offers a versatile platform for fast polarization measurements, enabling future developments in polarization imaging and advanced optical sensing applications.
We demonstrate a programmable terahertz (THz) metasurface enabling two-dimensional (2D) beam steering. Existing THz metasurfaces based on liquid crystal (LC) often provide insufficient continuous phase coverage, which li...We demonstrate a programmable terahertz (THz) metasurface enabling two-dimensional (2D) beam steering. Existing THz metasurfaces based on liquid crystal (LC) often provide insufficient continuous phase coverage, which limits the phase gradients required for synthesizing flexible and precise phase patterns. Here, we propose an orthogonally addressable architecture using dual H-shaped resonators in a reflective metal-LC-metal stack. The stacked resonators hybridize to form an electric quadrupole mode that localizes the field in the LC, while the coupled bilayer and the backside reflector establish a Fabry-Pérot (FP) cavity that further increases phase difference. As a result, a 300° continuous phase tuning is achieved by voltage control. Leveraging an orthogonal coding scheme to synthesize 2D phase gradients, we experimentally realize beam scanning with 5° steps up to angular range of ±40°. This work provides a scalable route toward intelligent THz apertures for communication and sensing.
A low-complexity non-integer fractionally spaced feed-forward equalizer (FFE) with half-symbol-spaced kernel estimation (HSSKE) is proposed for high-speed intensity modulation and direct detection (IM/DD) transmission sy...A low-complexity non-integer fractionally spaced feed-forward equalizer (FFE) with half-symbol-spaced kernel estimation (HSSKE) is proposed for high-speed intensity modulation and direct detection (IM/DD) transmission systems. By employing HSSKE, the proposed scheme enables accurate and aliasing-free kernel estimation at 2 samples per symbol (sps) while achieving efficient equalization at fractional sampling rates below 2 sps. Experimental results on a 100-GBaud/λ PAM-4 system over 1-km and 2-km standard single-mode fibers (SSMFs) demonstrate that the proposed 1.2-sps FFE with HSSKE not only outperforms 1.2-sps FFE with symbol-spaced estimation (SSKE) but also achieves equalization performance comparable to that of the conventional 2-sps FFE, while reducing computational complexity by more than 27%. Furthermore, when integrated with a noise whitening filter (NWF) and maximum likelihood sequence estimation (MLSE), the proposed scheme achieves a 0.9-dB improvement in receiver sensitivity compared to the 1.2-sps FFE with SSKE under the KP4-forward error correction (FEC) threshold of 2.4 × 10 over a 1-km link, and reduces the bit error rate (BER) below the 7% hard-decision FEC (HD-FEC) threshold of 3.8 × 10 after 2-km transmission.
The performance of perovskite light-emitting devices (PeLEDs) is frequently restricted by plasmonic losses at the metal-organic layer interface. Integrating micro-nano structures to mitigate these losses is a promising y...The performance of perovskite light-emitting devices (PeLEDs) is frequently restricted by plasmonic losses at the metal-organic layer interface. Integrating micro-nano structures to mitigate these losses is a promising yet challenging strategy. In this work, we employed a transfer-printed nanostructured hole transport layer (HTL) to achieve the nanostructured PeLEDs. This approach creates a periodic metal-dielectric interface that effectively outcouples non-radiative surface plasmon polariton (SPP) modes into radiative emission. Simultaneously, the nanostructured HTL spatially confines the perovskite film's nucleation and growth, yielding enhanced grain uniformity and surface coverage. Leveraging this dual optimization, all-inorganic CsPbBr3 PeLEDs achieve luminance and efficiency enhancements of 35.67% and 64.38%, respectively. These results demonstrate that transfer-printed nanostructures offer an effective pathway for optimizing both light extraction and film morphology in PeLEDs.
The real-time characterization of soliton interaction parameters is of great significance for improving the performance of passively mode-locked fiber lasers and exploring the general laws of dissipative nonlinear system...The real-time characterization of soliton interaction parameters is of great significance for improving the performance of passively mode-locked fiber lasers and exploring the general laws of dissipative nonlinear systems. Currently, the extraction of soliton dynamic parameters based on deep learning still relies on data labels and lacks physical analyzability. Here, we propose a new, to the best of our knowledge, unsupervised physical information embedding neural network that can unsupervisedly analyze real-time interferometric spectra of multi-soliton, achieving a more dimensional extraction of internal parameters of soliton molecules with a lighter neural network structure. We applied this model to analyze the dynamics of non-stationary double-soliton molecule and triple-soliton molecule, and the PCCs between the reconstructed dispersion Fourier transform spectra and the original dispersion Fourier transform spectra are higher than 0.94 and 0.9, respectively. This model effectively extracts dynamic parameters such as relative separation, relative phase, relative amplitude, and pulse width during soliton interaction, revealing the high-dimensional characteristics of soliton interaction.
A technique for rapid fluorescence excitation-emission matrix (EEM) measurements is proposed, which leverages the high optical throughput and tunable resolution of a scanning Michelson interferometer and the fast acquisi...A technique for rapid fluorescence excitation-emission matrix (EEM) measurements is proposed, which leverages the high optical throughput and tunable resolution of a scanning Michelson interferometer and the fast acquisition of a grating spectrometer. In this technique, a broadband excitation light beam is modulated by a galvanometer-scanning Michelson interferometer, and the resulting interferometrically modulated light excites the sample. By synchronizing fluorescence detection with galvanometer scanning, fluorescence spectra corresponding to different optical path differences are separated. This configuration enables the tradeoff between the excitation module's spectral resolution and measurement speed, while enabling high throughput excitation light focused into a small spot on the sample. It is demonstrated that with excitation and emission spectral resolutions of 10 nm and 0.44 nm, respectively, the system can acquire the EEM of an 8.34 μM Rhodamine 6 G solution in ethanol in only 977 ms.