We design an optical modulator based on an optical resonant cavity that coherently couples to an ensemble of nitrogen-vacancy (NV) centers, controlled by an external magnetic field. We reveal the coherent perfect absorpt...We design an optical modulator based on an optical resonant cavity that coherently couples to an ensemble of nitrogen-vacancy (NV) centers, controlled by an external magnetic field. We reveal the coherent perfect absorption (CPA) of photons in the system and demonstrate how to suppress, block, and amplify light transmission by manipulating the amplitude, direction, and detuning of the external magnetic field, as well as the phase difference between the input light fields. This design leverages the friendly controllability of NV centers by an external magnetic field, suggesting the potential to develop advanced photonic devices.
Ultrashort burst laser pulses are important for applications in laser processing and spectroscopy. However, existing burst generators face limitations in pulse time interval tunability and coaxiality. Here, we present a...Ultrashort burst laser pulses are important for applications in laser processing and spectroscopy. However, existing burst generators face limitations in pulse time interval tunability and coaxiality. Here, we present a burst pulse generator that delivers coaxial ultrashort pulses with tunable pulse time intervals using a single translation stage. The constructed system produced eight femtosecond pulses with uniform intervals tunable from 100 fs to 1.93 ns, equivalent to burst-internal repetition rates spanning 10 THz to 0.52 GHz. We further demonstrated interval-dependent plasma emission in air filamentation, providing a compact platform to study burst-laser-induced phenomena.
Spontaneous Raman scattering (SpRS) is a weak nonlinear effect particularly relevant to classical-quantum coexistence transmission and sensing applications. In classical transmission, the relevant Raman effect is stimula...Spontaneous Raman scattering (SpRS) is a weak nonlinear effect particularly relevant to classical-quantum coexistence transmission and sensing applications. In classical transmission, the relevant Raman effect is stimulated Raman scattering (SRS), and recent studies have examined it in space-division multiplexing (SDM) fibers. An intrinsic relation between SpRS and SRS allows previous SRS results to inform SpRS models. In this work, we extend SpRS models derived for single-mode fibers (SMFs) to SDM fibers with multiple mode groups of degenerate modes, covering both Stokes and anti-Stokes bands. The proposed model is a useful, fiber-design-independent tool for evaluating scattered noise in optical links, and it is validated through experimental measurements in field-deployed multi-core fibers (MCFs) and multi-mode fiber (MMF), showing good agreement.
This Letter presents a multimodal monitoring method based on combined fluorescence-coherence imaging for surface-interior polymer curing. The wavelength-selective absorption of fluorescence speckles is introduced to over...This Letter presents a multimodal monitoring method based on combined fluorescence-coherence imaging for surface-interior polymer curing. The wavelength-selective absorption of fluorescence speckles is introduced to overcome speckle occlusion, and three spectral channels are developed to eliminate signal crosstalk with ultraviolet excitation, blue-speckle surface imaging, and near-infrared tomography. For validation, a dedicated system integrating fluorescent digital image correlation (FDIC) and optical coherence tomography (OCT) is custom-built to measure the curing process. The result highlights significant advantages in spatial and mechanistic measurement. By resolving deformation from surface to interior, the depth-dependent response of local curing behaviors is demonstrated. Moreover, by merging FDIC's macroscopic stability and OCT's microscopic sensitivity, this method realizes mechanism coverage that is unattainable by either technique alone.
Broadband photodetectors that operate across the visible to infrared spectrum are vital for applications in environmental monitoring, biomedicine, remote sensing, imaging, and optical communications. However, most existi...Broadband photodetectors that operate across the visible to infrared spectrum are vital for applications in environmental monitoring, biomedicine, remote sensing, imaging, and optical communications. However, most existing devices require external bias, which undermines energy efficiency and slows response due to depletion-region perturbations. Here, we demonstrate a self-powered PtS/MoSe van der Waals heterostructure photodetector that leverages type-II band alignment to establish a built-in electric field, enabling efficient carrier separation without external bias. The device exhibits an ultralow dark current of ~10 A and a broadband response spanning 405-1064 nm. Under 532 nm excitation with a 0 V bias, it achieves a responsivity of 0.22 A W, a specific detectivity of 5.7 × 10 Jones, and an external quantum efficiency of 50.4%. Moreover, the heterostructure delivers high-quality imaging across the visible-infrared regime. These results highlight the PtS/MoSe heterostructure as a powerful platform for low-power, stable, and highly sensitive broadband photodetection, paving the way for advanced multispectral sensing and imaging technologies.
Traditional persistent luminescent materials are facing significant challenges in achieving multi-color anti-counterfeiting and visualization. Here, this study proposes a novel, to the best of our knowledge, multi-mode a...Traditional persistent luminescent materials are facing significant challenges in achieving multi-color anti-counterfeiting and visualization. Here, this study proposes a novel, to the best of our knowledge, multi-mode anti-counterfeiting strategy based on SrInGeO:x%Bi-y%Sm. By exploiting the energy transfer effect from Bi to Sm and adjusting the dopant concentration, continuous modulation of photoluminescence and afterglow emission from blue, yellow to orange is realized via regulating dopant concentrations. Based on systematic spectroscopic analysis, the corresponding energy transfer and afterglow mechanisms have been elucidated; this mechanism requires no complex multi-component doping systems and offers the advantages of ease of control and high stability. This work provides an effective strategy for developing multi-mode visual luminescent materials and broadens the application scope of afterglow phosphors in high-security information storage.
We demonstrate an acousto-optic sensing approach that integrates a dual-core AsSe nanofiber interferometer within a surface acoustic wave (SAW) cavity to achieve externally driven intermodal phase modulation distinct fro...We demonstrate an acousto-optic sensing approach that integrates a dual-core AsSe nanofiber interferometer within a surface acoustic wave (SAW) cavity to achieve externally driven intermodal phase modulation distinct from spontaneous forward Brillouin scattering. Introducing a thin liquid coupling layer allows Rayleigh SAW to satisfy the leaky wave condition causing radiation into the liquid, converting into a leaky SAW, enabling modulation sidebands and narrow detection bandwidths approaching the Hz level. Interferometric sensitivity is improved through coherent detection with balanced receivers and polarization biasing, acting as a common-mode noise rejection system, minimizing the optical noise floor to within ∼1 dB of the photodetector dark-noise limit.
A random fiber laser with an embedded external microresonator is shown to be capable of narrow-band generation with a stable single spectral line. Generation takes place right above the lasing threshold at a wavelength o...A random fiber laser with an embedded external microresonator is shown to be capable of narrow-band generation with a stable single spectral line. Generation takes place right above the lasing threshold at a wavelength of about 1.55 µm with a characteristic spectral width of less than 10 MHz. Generation wavelength remains stable for thousands of seconds, though it is sensitive to external acoustic noises or vibrations. With power increase, narrow-band generation becomes multimode with a spectrum consisting of numerous narrow lines. Here, the microcavity imposes the mode generation with the mode spacing that corresponds to the microresonator's free spectral range.
Vortex harmonic radiation from an indium tin oxide thin film in the epsilon-near-zero (ENZ) regime, driven by an ultrashort + 3 two-color field, is numerically investigated by solving the full-wave Maxwell equations wit...Vortex harmonic radiation from an indium tin oxide thin film in the epsilon-near-zero (ENZ) regime, driven by an ultrashort + 3 two-color field, is numerically investigated by solving the full-wave Maxwell equations with a nonlinear Kerr response. We show that the orbital angular momentum of the emitted harmonics provides a direct fingerprint of competing multiphoton pathways, because distinct photon-combination channels map onto harmonics with distinct topological charges and spatial profiles. For the fifth- and seventh-order harmonics, pathway competition is revealed through the evolution of intensity and spiral-phase structures with varying two-color amplitude ratios. Moreover, the ENZ regime is found to not only enhance harmonic generation but also preserve the topological stability of the emitted nonlinear modes.
We demonstrate the direct generation of a 160 W, high-purity Laguerre-Gaussian vortex beam (LG) from a Yb:Lu₂O₃ thin-disk laser oscillator. This is achieved through a synergistic thermal and loss management strategy. A s...We demonstrate the direct generation of a 160 W, high-purity Laguerre-Gaussian vortex beam (LG) from a Yb:Lu₂O₃ thin-disk laser oscillator. This is achieved through a synergistic thermal and loss management strategy. A strong, pump-induced thermal lens renders the resonator unstable for the fundamental LG mode, while an intracavity polarization-controlled output coupler provides tunable loss to suppress competing higher-order modes. This represents the highest, to the best of our knowledge, output power directly generated by an LG beam from any vortex laser oscillator, establishing a viable and scalable approach for high-power structured light sources.
In this work, a novel "1"-shaped acoustic cascaded resonator enhanced light-induced thermoelastic spectroscopy (LITES) gas sensing system is proposed for the first time, to the best of our knowledge. The designed resonat...In this work, a novel "1"-shaped acoustic cascaded resonator enhanced light-induced thermoelastic spectroscopy (LITES) gas sensing system is proposed for the first time, to the best of our knowledge. The designed resonator consists of three one-dimensional acoustic tubes, enabling cascaded amplification and efficient accumulation of acoustic energy in the LITES system. Finite element analysis (FEA) was employed to investigate the acoustic field distribution and optimize the key geometric parameters. Acetylene (CH) was selected as the target gas for validation. Compared with a conventional bare quartz tuning fork (QTF)-based LITES system, the proposed configuration achieved a 14.05-fold enhancement in the signal amplitude, and a minimum detection limit (MDL) of 3.1 ppm was obtained. Furthermore, the MDL was improved to 405 ppb at an average time of 200 s using Allan deviation analysis. The results demonstrate that the proposed multi-stage acoustic resonance strategy significantly enhances LITES performance and shows great potential for trace gas detection.
Accurate measurement of optical transfer delay (OTD) in multiple channels is crucial for applications such as optical phased array antennas, distributed fiber-optic sensors, and high-capacity multichannel optical communi...Accurate measurement of optical transfer delay (OTD) in multiple channels is crucial for applications such as optical phased array antennas, distributed fiber-optic sensors, and high-capacity multichannel optical communications. However, conventional high-accuracy microwave photonic phase-derived measurement techniques are limited to single-channel operation, where multi-channel measurements are typically performed sequentially via optical switching, resulting in low measurement efficiency. In this paper, we propose and experimentally demonstrate a high-accuracy, parallel multi-channel OTD measurement technique based on time-gated phase-based ranging. Wavelength division multiplexing (WDM) is employed to distribute multi-wavelength probe signals to multiple channels. Each wavelength corresponds to a specific channel, enabling parallel excitation and single-receiver detection, which significantly simplifies the system architecture. Although reflections from multiple channels overlap in the frequency domain, the proposed method separates individual channel responses in the time domain. The phase response of each channel is then retrieved via time-domain gating and frequency-domain processing, allowing high-accuracy delay extraction through the linear slope of the unwrapped phase. Experimental results demonstrate simultaneous parallel measurement of 8 channels with a measurement precision of ±0.25 ps. Featuring a simple architecture, high precision, and multi-channel scalability, the proposed technique provides an efficient solution for the characterization of complex optical networks and multi-core fiber systems.
Two-photon microscopy (TPM) enables deep, minimally invasive volumetric imaging of biological tissues, but its three-dimensional (3D) spatial resolution is fundamentally limited by diffraction, particularly along the axi...Two-photon microscopy (TPM) enables deep, minimally invasive volumetric imaging of biological tissues, but its three-dimensional (3D) spatial resolution is fundamentally limited by diffraction, particularly along the axial direction. Here, we present a 3D resolution enhancement strategy for TPM by combining point spread function (PSF) engineering with multi-image deconvolution. By redistributing the objective pupil, we generate a modulated excitation PSF with enhanced axial high-frequency components. Two complementary volumetric datasets acquired under conventional Gaussian and modulated illumination are then jointly reconstructed using a Hessian-regularized deconvolution framework. Experiments on 200-nm fluorescent beads demonstrate lateral and axial resolution improvements of 1.56× and 1.67×, respectively, over conventional TPM, with a further 1.26× axial improvement relative to deconvolution using only the Gaussian-PSF image. Imaging of actin filaments in HeLa cells confirms improved contrast and visualization of fine 3D structures. Brain-slice experiments further show that aberrations can severely compromise performance, whereas aberration correction restores the axial-resolution enhancement. These results establish PSF engineering combined with multi-image deconvolution as an effective route for enhancing 3D resolution in TPM.
The tuning of the fractional orbital angular momentum of an optical vortex beam is proposed and experimentally demonstrated using a common-path stable technique by controlling the enantiomeric excess of an optically acti...The tuning of the fractional orbital angular momentum of an optical vortex beam is proposed and experimentally demonstrated using a common-path stable technique by controlling the enantiomeric excess of an optically active material in an enantiomeric mixture. The projection of the generated vector vortex beam onto horizontal polarization results in an optical vortex beam with its vortex position at the center. The radial position of the optical vortex is controlled by passing the vector vortex beam through an enantiomeric mixture and controlling the enantiomeric excess of an optically active material. The orbital angular momentum of the resulting off-axis beams is measured as a function of different enantiomeric excesses using a cylindrical lens and intensity moments. The results are compared with those of diagonal polarization projection. The non-canonical nature of the generated off-axis vortex is also characterized using Fourier fringe analysis. These results can be useful in optical micro manipulation and also in the detection of enantiomeric impurities.
A novel, to the best of our knowledge, sensor based on the controlled collapse of the hollow core of a thin-wall silica capillary tube (SCT) spliced between two single-mode fibers is proposed for the monitoring of extern...A novel, to the best of our knowledge, sensor based on the controlled collapse of the hollow core of a thin-wall silica capillary tube (SCT) spliced between two single-mode fibers is proposed for the monitoring of external liquid refractive index (RI). The conical shape of the splice excites multimodal interference in the cladding of the SCT. For a range of 1.333-1.341 RIU, when isolating the dominant frequencies, a maximum sensitivity of 4421 nm/RIU is achieved, which is an outstanding result for an all-silica-based device in this RI range. The low-cost one‑step fabrication process, in conjunction with the ultrahigh sensitivity, displays remarkable potential for real‑time detection in chemical processing applications, where precise RI monitoring is required.
We propose what we believe to be a novel holographic recording technique to improve the recording speed for holographic data storage (HDS). In this technique, holograms are recorded by scanning a digital micromirror devi...We propose what we believe to be a novel holographic recording technique to improve the recording speed for holographic data storage (HDS). In this technique, holograms are recorded by scanning a digital micromirror device (DMD) that displays a data page with a focused, power density-increased line beam while synchronously shifting the recording medium and a spherical reference wave. This approach eliminates the stop-and-go motion of driving mechanisms, enabling rapid, continuous, multiplexed recording. Although the recorded localized holograms retain only partial information about the data page, the entire page can be reconstructed simultaneously using the spherical reference wave. Experimental demonstrations achieved a bit error rate (BER) of less than 10% at a 5ms exposure time and stable multiplexed recording at 150Hz. The proposed technique represents a significant step toward the realization of practical HDS systems.
We propose and demonstrate a surface plasmon resonance (SPR) sensor using metallic niobium diselenide (NbSe). A BK7/Cr/Au/NbSe multilayer was modeled to investigate the layer-number-dependent sensing performance. The sim...We propose and demonstrate a surface plasmon resonance (SPR) sensor using metallic niobium diselenide (NbSe). A BK7/Cr/Au/NbSe multilayer was modeled to investigate the layer-number-dependent sensing performance. The simulated angular sensitivity first increases and then decreases with NbSe layer number, reaching 273 deg/RIU for six-layer NbSe within the investigated range. X-ray photoelectron spectroscopy confirms NbSe deposition on Au. Refractive-index experiments agree with the simulations and give a sensitivity of 286.38 deg/RIU for the Au/NbSe structure, higher than those of bare Au, Au/BP, and Au/graphene structures. Glucose sensing shows a linear response from 10 to 500 ng/mL, corresponding to 55.5 nM to 2.78 μM, and a limit of detection of 2.73 ng/mL, corresponding to 15.2 nM. These results provide a practical strategy for high-sensitivity SPR sensing platforms based on metallic two-dimensional materials.
Phase-only holograms are often loaded onto liquid crystal on silicon (LCOS) spatial light modulators (SLMs) to realize three-dimensional (3D) holographic displays. However, the fringing field effect of LCOS-SLMs severely...Phase-only holograms are often loaded onto liquid crystal on silicon (LCOS) spatial light modulators (SLMs) to realize three-dimensional (3D) holographic displays. However, the fringing field effect of LCOS-SLMs severely degrades the reconstruction quality of holograms. Here, we propose an accurate method to measure the crosstalk induced by the fringing field effect of SLMs and present a novel, to the best of our knowledge, superpixel-based complex amplitude modulation hologram solved via gradient descent to compensate for the fringing field effect. Our hologram realizes complex amplitude modulation with a phase-only SLM without increasing the sampling interval, compensates for the crosstalk caused by the fringing field effect, and achieves a high-quality speckle-free color 3D holographic display.
Functional splitting in next-generation mobile networks enables new opportunities for millimeter wave radio over fiber systems. Since a cell-free network architecture is a possible way to enable uniform high data rates,...Functional splitting in next-generation mobile networks enables new opportunities for millimeter wave radio over fiber systems. Since a cell-free network architecture is a possible way to enable uniform high data rates, we propose a scalable optical full-duplex crosshaul with simplified radio units, where a low-cost directly modulated laser transmits a 1.5 GHz intermediate frequency uplink signal. The scheme is experimentally validated over a seamless antenna channel, showing efficient operation at 40 GHz. System performance is verified for bandwidths up to 400 MHz using 5 G modulation formats, with the error vector magnitude remaining well below standard limits.
Low-saturation structural colors, such as muted or pastel hues, offer visual comfort, reduced eye fatigue, and aesthetic versatility for human-centric optical applications yet remain largely unexplored compared to their...Low-saturation structural colors, such as muted or pastel hues, offer visual comfort, reduced eye fatigue, and aesthetic versatility for human-centric optical applications yet remain largely unexplored compared to their vivid counterparts. Here, we numerically investigate a thermally tunable metasurface that generates such colors by leveraging symmetry-protected bound states in the continuum (SP-BICs). Introducing controlled asymmetry into a dual-period silicon grating on a metallic substrate activates high-Q quasi-BIC resonances, selectively absorbing narrow spectral bands while maintaining >90% reflectance elsewhere. This results in structural colors with saturation below 10% in the CIE 1931 space. Integrated joule heating enables dynamic tuning of the absorption peak (~0.1 nm/K), allowing continuous control of pastel hues from 460 to 520 nm. As a simulation-based proof of concept, this design provides a promising route toward eye-friendly displays, low-glare optical labeling, and thermal sensing where low-saturation coloration is desired.