Femtosecond laser direct writing is highly effective for fabricating three-dimensional photonic waveguides deep inside ultra-hard crystals. Extending this capability to the surface realm, where waveguides interact direct...Femtosecond laser direct writing is highly effective for fabricating three-dimensional photonic waveguides deep inside ultra-hard crystals. Extending this capability to the surface realm, where waveguides interact directly with the sample interface, has been challenging due to pronounced susceptibility to structural cracking. To address this, we introduce a strategy that avoids direct laser modification of fragile crystal-air interfaces. Our approach employs a novel, to the best of our knowledge, surface-integrated, partial-ring cladding architecture, unlike the conventional full-ring design for buried waveguides. By precisely controlling the laser focal depth and cladding geometry, we demonstrate crack-free surface waveguides in sapphire with strong optical confinement and a propagation loss of ~2 dB/cm at 1500-1600 nm. Experiments and simulations confirm that buried waveguides with full-ring cladding support near-Gaussian modes, whereas partial-ring surface waveguides exhibit minor modal distortion owing to interfacial effects. This work advances the integration of high-performance surface waveguides in hard optical materials for applications in surface sensing and photonic circuits.
A single-sideband laser heterodyne spectrometer (LHS) was developed for the first time, to the best of our knowledge. A multi-channel configuration employing different band-pass filters and frequency-shifted LOs achieves...A single-sideband laser heterodyne spectrometer (LHS) was developed for the first time, to the best of our knowledge. A multi-channel configuration employing different band-pass filters and frequency-shifted LOs achieves single-sideband detection at the hardware level, thereby eliminating the central dip distortion inherent in conventional dual-sideband LHS. The operation of the single-sideband LHS was analyzed and experimentally validated through optimization of the frequency shift of acousto-optic modulators and the bandwidth of radio-frequency filters, yielding a two-fold enhancement in spectral resolution. The performance of the single-sideband LHS was evaluated and validated through measurements of methane absorption spectra. The results demonstrate a significant improvement in spectral fidelity, with the error reduced by 64% compared with conventional dual-sideband LHS. The single-sideband LHS reported in this paper is expected to provide a powerful tool with high spectral resolution and high accuracy for remote sensing of upper atmospheric gases and planetary atmospheric molecules.
Addressing the limited adaptability of traditional air humidity detection technology in complex environments, a multimodal air humidity recognition system based on the fusion of laser-induced breakdown spectroscopy (LIBS...Addressing the limited adaptability of traditional air humidity detection technology in complex environments, a multimodal air humidity recognition system based on the fusion of laser-induced breakdown spectroscopy (LIBS) and laser-induced plasma acoustics (LIPA) combined with machine learning is proposed for the first time, to the best of our knowledge. The experiment verified the synergistic effect of LIPA and LIBS for what we believe is the first time: the spectral intensity of hydrogen atoms in LIBS increases with the increase of relative air humidity, while the LIPA signal exhibits humidity-specific acoustic characteristics, with complementary information between the two. Principal Component Analysis (PCA) was used to reduce dimensionality and extract features from LIBS and LIPA data, followed by a Decision Tree (DT) model to classify the four humidity levels. The fusion data achieves a classification accuracy of 100%, significantly outperforming single LIBS technology. This study verifies the feasibility of the fusion technology, provides a new solution for high-precision humidity monitoring, and is of pioneering significance.
Optical super-resolution microscopy under surface plasmon illumination has been proven to realize an ultra-high imaging resolution based on the deep Spatial Frequency Shift (SFS) effect. However, SFS super-resolution ima...Optical super-resolution microscopy under surface plasmon illumination has been proven to realize an ultra-high imaging resolution based on the deep Spatial Frequency Shift (SFS) effect. However, SFS super-resolution imaging always suffers from loss of spatial frequencies (SFs) between the cutoff frequency and the modulated high SF, which leads to image distortion. Here, a wavelength-encoded multi-wavevector excitation (WEME) method is proposed for filling the SF gap under plasmonic illumination in label-free super-resolution imaging. The dispersion properties of the multilayer film enable surface plasmon polariton (SPP) illumination modes with various lateral wavevectors (), making it possible to obtain different depths of SFS supported by the same multilayer structure at designed wavelengths. We experimentally demonstrated that a large SF span of 4NA/ (NA/∼5/) can be detected, which supports the reconstruction of real-size super-resolution images using only three frames. WEME experimentally provides a universal approach for efficient ultra-high resolution imaging under high- SPP illumination to detect the nanostructures with a scale varying from sub-100 nm to sub-1 µm.
Accurate histological analysis plays an irreplaceable role in disease diagnosis. Although virtual staining has alleviated some of the costly and tedious steps involved in histochemical staining processes, most methods em...Accurate histological analysis plays an irreplaceable role in disease diagnosis. Although virtual staining has alleviated some of the costly and tedious steps involved in histochemical staining processes, most methods employ low-throughput inputs, potentially limiting accurate reconstruction of tissue architecture. In this paper, a high-throughput virtual staining framework is proposed to achieve robust characterization of tissue structural features with extended depth-of-field by integrating information across visible (VIS) and near-infrared (NIR) ranges from 10-µm-thick tissue sections. A multispectral microscopic imaging system is constructed to acquire multispectral information. HSSNet is established to efficiently extract high-dimensional spectral features, achieving accurate mapping from plain multispectral transmittances to stained RGB images. Experimental results on liver cancer across multiple differentiation grades demonstrate that our method maintains high color fidelity and reliably reconstructs the differentiation-dependent tissue structural features, providing a promising paradigm for extending virtual staining into histopathological assessment of heterogeneous tumors.
Non-radiative relaxation hinders the performance of erbium-based mid-infrared lasers. Here, we demonstrate that anion-engineering in fluorite crystal provides a solution to this challenge, facilitating efficient laser op...Non-radiative relaxation hinders the performance of erbium-based mid-infrared lasers. Here, we demonstrate that anion-engineering in fluorite crystal provides a solution to this challenge, facilitating efficient laser operation. The Er,Se-co-doped CaF crystal exhibits extended lifetimes at characteristic emission bands compared to Er:CaF. First-principles calculations reveal the spatial proximity of Se to Er clusters within CaF lattice, alongside the introduction of low-frequency phonon modes, underpinning the observed phenomena. Efficient 2.75 µm continuous-wave laser operation was demonstrated on this crystal, exhibiting high slope efficiencies of 34.4% and 12.2% under 976 nm resonant and 1532 nm upconversion pumping, respectively. Our results highlight the role of anion-engineering in designing advanced laser materials.
We obtain a complete characterization of a vectorial, random light beam carrying orbital angular momentum (OAM) across modes in its 2-dimensional polar Fourier space defined by the Modelization Matrix (MM), whose elemen...We obtain a complete characterization of a vectorial, random light beam carrying orbital angular momentum (OAM) across modes in its 2-dimensional polar Fourier space defined by the Modelization Matrix (MM), whose elements are scalar radial field correlations filtered at the pairs of OAM and polarization components. The MM is shown to encode a fully structured state uniquely represented by an ellipse, providing a geometrical signature of the beam. Various measures quantifying the modal weight distribution and coupling of the beam are introduced. A numerical example is presented for visualization.
We report a kilowatt-class Yb:YO ceramic thin-disk laser enabled by a diamond heat sink. Under 976 nm diode pumping, continuous-wave (CW) output power of 1089 W at 1031.7 nm is achieved with an optical-to-optical efficie...We report a kilowatt-class Yb:YO ceramic thin-disk laser enabled by a diamond heat sink. Under 976 nm diode pumping, continuous-wave (CW) output power of 1089 W at 1031.7 nm is achieved with an optical-to-optical efficiency of 73%. To the best of our knowledge, this is the first demonstration of kilowatt-class output from a Yb:YO ceramic gain medium. Moreover, the optical-to-optical efficiency obtained in the experiment represents the highest reported among all sesquioxide ceramic thin-disk lasers, indicating that Yb:YO ceramics are promising gain media for high-power and high-efficiency laser systems.
Thin-film lithium tantalate (TFLT) is considered a key next-generation platform for integrated photonics due to its strong electro-optic effect and low propagation loss. This work demonstrates for the first time, to the...Thin-film lithium tantalate (TFLT) is considered a key next-generation platform for integrated photonics due to its strong electro-optic effect and low propagation loss. This work demonstrates for the first time, to the best of our knowledge, the design and fabrication of a photonic crystal ring resonator (PhCR) along with its electro-optic modulator on TFLT. The fabricated PhCR achieves high quality factors of 2.16 × 10⁵ and 1.08 × 10⁵ in the air and dielectric bands, respectively, and a pronounced slow-light effect (with a slow-light factor S > 3). This confirms the platform's capability to support both high-Q optical resonance and effective dispersion engineering. The PhCR modulator, constructed with a reduced bending radius, features a low half-wave voltage-length product of 1.71 V·cm and an electro-optic bandwidth of 44 GHz, demonstrating its potential for high-speed signal processing. This work fills a critical gap for slow-light photonic crystal devices on TFLT and establishes an experimental foundation for future active and multifunctional slow-light photonic devices on this platform.
We present the employment of wavefront imaging using Quadriwave Lateral Shearing Interferometry (QLSI) for Optical Diffraction Tomography (ODT) reconstructions. Compared to a conventional Digital Holographic (DH) Interfe...We present the employment of wavefront imaging using Quadriwave Lateral Shearing Interferometry (QLSI) for Optical Diffraction Tomography (ODT) reconstructions. Compared to a conventional Digital Holographic (DH) Interferometer, QLSI does not require a reference beam. It can also work efficiently with an incoherent source and hence reduces the speckle noise. Furthermore, QLSI is almost insensitive to phase wrapping, thus avoiding artefacts and easing the signal processing in ODT. We validate the method by reconstructing the 3D refractive index (3DRI) of a polystyrene bead via angle-scan diffraction tomography. The 3DRI reconstruction of the nano-printed phantom cell and the living yeast cell is also presented.
During daylight operation, sunlight propagates in reverse along the imaging path of a head-up display (HUD) through the windshield. Sunlight is then concentrated on the display panel, thereby degrading reliability. The s...During daylight operation, sunlight propagates in reverse along the imaging path of a head-up display (HUD) through the windshield. Sunlight is then concentrated on the display panel, thereby degrading reliability. The sunlight backflow should be eliminated while not affecting the display function, especially in the visible spectrum. This study proposes a new, to the best of our knowledge, architecture incorporating a nonreciprocal optical isolator, i.e., a Faraday rotator, to eliminate sunlight backflow. Further, given the étendue constraint imposed by the small aperture of practical Faraday rotators, a time-multiplexing scheme doubles the effective étendue to create two distinct virtual image distances while fully utilizing the Faraday rotator's aperture-limited étendue. An LCD-based prototype demonstrated a sunlight-isolation rate of 3.23% in terms of irradiance (unit: W/m) across the visible spectrum. Meanwhile, the Faraday rotator exhibited uniform, high transmittance across the visible band for forward light from the LCD, yielding a satisfactory forward luminous (unit: cd/m) efficiency of 86.1% with negligible color cast.
Light propagation is typically hindered by obstacles along its path. A common strategy is therefore to shape the light field so that it avoids interacting with them, an idea recently popularized by invisibility cloaks. P...Light propagation is typically hindered by obstacles along its path. A common strategy is therefore to shape the light field so that it avoids interacting with them, an idea recently popularized by invisibility cloaks. Previous studies have shown that transmission can be achieved either by steering light around localized objects or, when apertures are present, by guiding it through them-both mechanisms being well described by ray optics. Here, we show that a specific class of obstacles with no direct line of sight can nonetheless transmit light. Experimentally, we demonstrate a transmission of 27 through a set of three masks lacking any direct line of sight, enabled by proper wavefront engineering using a microlens array. This effect, based on a reinterpretation of the Talbot effect, is captured by the generalized eikonal equation. Our results provide a striking counterexample to the long-standing ray-optics picture that light propagates in straight lines in homogeneous media.
We report a high-performance electromagnetic micro-electro-mechanical-system (MEMS) fast steering mirror (FSM) designed to meet the pressing need for miniaturized laser communication terminals on small low-earth-orbit (L...We report a high-performance electromagnetic micro-electro-mechanical-system (MEMS) fast steering mirror (FSM) designed to meet the pressing need for miniaturized laser communication terminals on small low-earth-orbit (LEO) satellites. With a 10 mm optical aperture, the device employs a gimbal structure driven by orthogonal magnetic field components to achieve biaxial decoupling and high linearity. A bipolar magnetic configuration augments the driving torque, providing sufficient design margin for the torsion axis while reducing power consumption. Additionally, T-shaped torsion beams are utilized to enhance shock robustness without compromising the scanning range. Experimental results demonstrate a mechanical tilt of ±2.3 mrad@±52 mA with a low holding power of 54 mW per axis. Nonlinearity is only 0.04%. Resonant frequencies of 598 Hz and 819 Hz are achieved, enabling a rise time of 0.38 ms and a closed-loop 2% settling time of approximately 1.0 ms. Furthermore, the structural failure of the torsion beams was observed at a shock load of 960 g. This work provides a robust, power-efficient, and high-precision beam-steering solution for optical communication terminals on small LEO satellites.
Vector vortex beams (VVBs) with simultaneous helical phase and non-uniform polarization distributions are attracting extensive research interest due to their unique properties. However, achieving arbitrary, tunable-order...Vector vortex beams (VVBs) with simultaneous helical phase and non-uniform polarization distributions are attracting extensive research interest due to their unique properties. However, achieving arbitrary, tunable-order, and high-power VVBs remains a challenge. We proposed a vector vortex alkali amplifier with the potential to generate high-power VVBs. By sending a shaped vector vortex seed beam into an alkali amplifier, we obtained an output power of 4.41 W under the condition of both polarization order and topological charge equal to 1, with a gain of 22.45 dB @2 cm, which exhibits a mode fidelity of 88.2% and single-frequency characteristics. This setup enables the generation of high-power VVBs corresponding to arbitrary poles on the hybrid-order Poincaré sphere, exhibiting potential applications in optical sensing, quantum technologies, optical communications, and other related fields.
This work proposes a gap-opening double-elliptical cylinder metamaterial that achieves dual polarization multi-resonance mode synergistic excitation by introducing out-of-plane symmetric breaking. Under TE polarization,...This work proposes a gap-opening double-elliptical cylinder metamaterial that achieves dual polarization multi-resonance mode synergistic excitation by introducing out-of-plane symmetric breaking. Under TE polarization, an exceptionally high Q-factor (4.27 × 10) of quasi-BIC (Mode 1) is realized, with excellent sensing sensitivity of 750 GHz/RIU, whereas two different quasi-BIC modes (called Mode 2 and Mode 3) are gained under TM polarization. In particular, the near-field coupling of Mode 2 and guided-mode resonance (GMR) gives rise to an electromagnetically induced transparency (EIT), whose performance could be flexibly controlled by precisely tuning the structural asymmetry and other relevant parameters, thereby offering versatile spectral tunability. Multipole decomposition and near-field analysis reveal the formation mechanisms of dual-polarization multi-resonance modes. Our results could have application prospects in fields such as beamforming and biomedical sensing.
We numerically demonstrate a compact hybrid metasurface enabling low-voltage and dual-field control of enhanced Faraday rotation in the sub-terahertz regime. The structure combines a thin-film antiferromagnet (MnF), exhi...We numerically demonstrate a compact hybrid metasurface enabling low-voltage and dual-field control of enhanced Faraday rotation in the sub-terahertz regime. The structure combines a thin-film antiferromagnet (MnF), exhibiting resonance near 268 GHz, with TiO-based memristive resonators whose plasma frequency is electrically tunable. Resonant quasi-crossing between antiferromagnetic and electronic modes results in more than sixfold enhancement of the polarization rotation compared to a bare antiferromagnetic layer. Continuous tuning of the rotation angle is achieved via simultaneous application of static magnetic and DC electric fields. Voltage-driven modulation below 1 V provides efficient electrical control of the magneto-optical response without requiring strong magnetic bias variation. The proposed platform offers a compact and energy-efficient route toward reconfigurable polarization control in sub-THz photonics, with potential applications in tunable isolators, modulators, and hybrid quantum transduction systems.
Transparent dielectrics are essential in advanced photonic, electronic, and medical devices owing to their excellent properties, but these very properties also make efficient micromachining difficult, particularly for hi...Transparent dielectrics are essential in advanced photonic, electronic, and medical devices owing to their excellent properties, but these very properties also make efficient micromachining difficult, particularly for high-aspect-ratio deep-hole fabrication. Here, we demonstrate a dual-beam approach that enables 153-µm-deep hole drilling within an effective processing time of 50 ps. In this scheme, a high-angle Bessel beam generates a highly absorptive filament, while a perpendicular, cylindrically focused pulse delivers energy to the filament vicinity. Compared with recent GHz Bessel-burst drilling, which typically relies on multiple pulses separated by several hundred picoseconds and therefore requires a total processing window on the order of nanoseconds, the present approach achieves analogous filament-assisted deep drilling in a compressed temporal window. This result highlights the potential of the proposed scheme as a new strategy for single-shot, high-aspect-ratio micromachining of transparent dielectrics and may provide a basis for future improvements in practical processing throughput through further development of system-level implementation strategies.
In this Letter, a line-scan phase measuring deflectometry (LSPMD) method for online three-dimensional (3D) shape reconstruction of specular surfaces is proposed for the first time, to the best of our knowledge. Differing...In this Letter, a line-scan phase measuring deflectometry (LSPMD) method for online three-dimensional (3D) shape reconstruction of specular surfaces is proposed for the first time, to the best of our knowledge. Differing from conventional PMD systems, LSPMD exploits a line-scan camera and a high-framerate sinusoidal fringe display screen to realize an ultrafast fringe acquisition rate and sufficient resolution. Furthermore, based on the novel hardware architecture and acquisition logic, a flexible and robust system calibration method for LSPMD using a geometrically defined surface is specifically proposed, which enables high-precision 3D reconstruction without camera calibration and additional auxiliary patterns. The experimental results illustrate that LSPMD simultaneously achieves an ultra-high acquisition rate of 10 kHz and a high pixel resolution of 8132 pixels.
We propose a theoretical framework based on ideal dispersion to achieve broadband perfect absorption in thin-film structures with alternating lossy and dielectric layers. Using the Airy formula, the ideal dispersion rela...We propose a theoretical framework based on ideal dispersion to achieve broadband perfect absorption in thin-film structures with alternating lossy and dielectric layers. Using the Airy formula, the ideal dispersion relation of the lossy material required for perfect absorption is analytically derived, providing explicit guidance for material selection and layer-thickness design. Thin-film absorbers designed and fabricated for the visible and near-infrared bands exhibit average absorptances exceeding 0.97, in agreement with theoretical predictions. This framework is extendable to other spectral ranges, offering a reliable route toward high-performance, customizable optical absorbers.
This study investigates drawing-induced effects on bismuth active centers (BACs) and optical amplification in Bi-doped phosphosilicate fibers operating in E and S bands. A twofold increase in BAC-related active absorptio...This study investigates drawing-induced effects on bismuth active centers (BACs) and optical amplification in Bi-doped phosphosilicate fibers operating in E and S bands. A twofold increase in BAC-related active absorption was observed, while the unsaturable loss remained nearly constant over a 100 °C drawing temperature. Unitary gain (dB/m) was found to increase linearly with drawing temperature, reaching ∼0.4 dB/m under bi-directional pumping when using 390 mW. With this pumping configuration, the amplifier's unsaturated peak gain was close to 35 dB using an optimum fiber length less than 100 m, demonstrating efficient amplification with high Bi concentration in those fibers.