
- Feb. 18, 2025
- Vol. 23, Issue 1 (2025)
- Feb. 17, 2025
- Vol. 22, Issue 12 (2025)
- Feb. 17, 2025
- Vol. 12, Issue 12 (2025)
- Feb. 14, 2025
- Vol. 12, Issue 12 (2025)
- Feb. 14, 2025
- Vol. 12, Issue 11 (2025)
The unique phase profile and polarization distribution of the vector vortex beam (VVB) have been a subject of increasing interest in classical and quantum
The unique phase profile and polarization distribution of the vector vortex beam (VVB) have been a subject of increasing interest in classical and quantum optics. The development of higher-order Poincaré sphere (HOPS) and hybrid-order Poincaré sphere (HyOPS) has provided a systematic description of VVB. However, the generation of arbitrary VVBs on a HOPS and a HyOPS via a metasurface lacks a unified design framework, despite numerous reported approaches. We present a unified design framework incorporating all design parameters (e.g., focal lengths and orders) of arbitrary HOPS and HyOPS beams into a single equation. In proof-of-concept experiments, we experimentally demonstrated four metasurfaces to generate arbitrary beams on the fifth-order HOPS (nonfocused and tightly focused, NA 0.89), 0-2 order, and 0-1 order HyOPS. We showed HOPS beams’ propagation and focusing properties, the superresolution focusing characteristics of the first-order cylindrical VVBs, and the different focusing properties of integer-order and fractional-order cylindrical VVBs. The simplicity and feasibility of the proposed design framework make it a potential catalyst for arbitrary VVBs using metasurfaces in applications of optical imaging, communication, and optical trapping.show less
- Feb.18,2025
- Advanced Photonics Nexus,Vol. 4, Issue 1
- 016015 (2025)
Two-photon microscopy provides sectioned excitation, but in practical settings, it often suffers from contrast limitations. Here, we report the observatio
Two-photon microscopy provides sectioned excitation, but in practical settings, it often suffers from contrast limitations. Here, we report the observation of a strong acousto-optic modulation of two-photon excited fluorescence. Harnessing this effect yields enhanced image detail and contrast and improves optical sectioning in deep brain tissue in vivo. Ultrasound-modulation assisted multiphoton imaging (UMAMI) is compatible with standard multiphoton microscopes, without requiring changes to the optical path or image acquisition parameters.show less
- Feb.18,2025
- Advanced Photonics,Vol. 6, Issue 6
- 066003 (2024)
The retroreflector based on a gradient metasurface can reflect electromagnetic (EM) waves to the source, and it is small in size and lightweight. However,
The retroreflector based on a gradient metasurface can reflect electromagnetic (EM) waves to the source, and it is small in size and lightweight. However, even if the previous retroreflectors can be used for angle adaptation, the working efficiency declines sharply at large angles. In this paper, a retroreflector is designed based on a reconfigurable origami two-dimensional (2D) metagrating for efficient spin-locked retroreflection and for suppressing unwanted Floquet diffraction channels. After the retroreflection, the handedness of the wave remains consistent with the incident. By changing the folding state of the origami metagrating, the adaptive tangential momentum can be transferred to the incident wave, providing high-performance retroreflection over a continuous incidence angle range of 30°–45.8° (x-direction) and 30°–81° (y-direction). As proof of concept, an electric metagrating-based retroreflector is fabricated in the microwave frequency band, and the simulation and experimental results are consistent. This adaptive origami spin-locked metasurface has promising applications in spin-optics devices, communication systems, remote sensing, and radar cross-section (RCS) enhancement.show less
- Feb.17,2025
- Chinese Optics Letters,Vol. 23, Issue 1
- 010501 (2025)
This paper presents a wavelength-stepped swept laser based on a dispersion-tuned swept laser with the integration of a Mach–Zehnder interferometer, enabli
This paper presents a wavelength-stepped swept laser based on a dispersion-tuned swept laser with the integration of a Mach–Zehnder interferometer, enabling a transition from continuous wavelength sweeping to wavelength-stepped sweeping. A comprehensive investigation of this laser is conducted, wherein different modulation schemes are employed to dynamically compare the switching mode, static-sweeping mode, and sweeping mode; the absence of mode hopping in the sweeping mode of the laser is verified. However, it is observed during experiments that the wavelength always remains stationary for a long time during the initiation of sweeping and change in sweeping direction, exhibiting latency compared to the modulation frequency variations. Through a simplistic modeling analysis of the composite cavity, it is revealed that the detuned state of the sub-cavity plays a critical role in the stable operation of the laser. Subsequently, simulation verification using the Ginzburg–Landau equation supports this observation. Additionally, compared to dispersion-tuned swept lasers, not only the linewidth significantly is narrowed in the proposed laser, but it also demonstrates enhanced stability during the sweeping process. This study provides, to our knowledge, a new laser source for ultra-fast optical imaging, ranging, and sensing applications, and presents novel methods and theoretical models for linewidth compression in swept lasers.show less
- Feb.14,2025
- Photonics Research,Vol. 13, Issue 3
- 604 (2025)
We presented a repetition-rate tunable Yb-doped fiber laser system, which used a chirped fiber Bragg grating as a fiber stretcher designed to match the 2nd and 3rd order dispersion of the transm
We presented a repetition-rate tunable Yb-doped fiber laser system, which used a chirped fiber Bragg grating as a fiber stretcher designed to match the 2nd and 3rd order dispersion of the transmission grating compressor. The system delivered 1-μJ, 143-fs pulse at 2 MHz repetition rate, and 10-μJ, 157-fs pulse at 200 kHz repetition rate, respectively. Pulse repetition-rate can be tuned from 200 kHz to 2 MHz while the pulse duration maintains <180 fs. This compact fiber laser source was built for applications in ophthalmology, such as corneal flap cutting and tissue vaporization. Furthermore, it can be applied in micro-machining, such as laser marking, scribing, and drilling.show less
- Feb.17,2025
- Chinese Optics Letters,Vol. 23, Issue 7
- (2025)
A microwave photonic subsampling digital receiver (MPSDR) is proposed and experimentally demonstrated for target detection with a sampling rate of 10 MSa/s. Stepped and pseudo-random frequency-h
A microwave photonic subsampling digital receiver (MPSDR) is proposed and experimentally demonstrated for target detection with a sampling rate of 10 MSa/s. Stepped and pseudo-random frequency-hopping signals with frequencies across the K band are both used for target detection and can be captured by the MPSDR. The range profiles of the targets are then derived by using a compressed sensing algorithm and precise target position estimation is achieved by changing the measurement position of the antenna pair. The results demonstrate that the estimation accuracy remains comparable even when the pseudo-random frequency-hopping signal utilizes only 12.5% of the frequency points required by the stepped frequency-hopping signal. This highlights the efficiency and potential of the proposed MPSDR in processing complex signal while maintaining high accuracy.show less
- Feb.17,2025
- Chinese Optics Letters,Vol. 23, Issue 7
- (2025)
A cross air-water interface hydroacoustic signal detection method based on micro vibration detection at the air-water interface is proposed. Laser speckles modulated by water surface acoustic wa
A cross air-water interface hydroacoustic signal detection method based on micro vibration detection at the air-water interface is proposed. Laser speckles modulated by water surface acoustic wave are recorded and used as information carrier. Phase correlation and multi-channel fusion algorithms are used to extract and enhance hydroacoustic signals. Wide frequency range (200 Hz-20 kHz) underwater acoustic signals are detected with frequency relative error smaller than 0.5%. Several common artificial and natural hy-droacoustic signals are used as source signals and correctly reconstructed. The average intelligibility of recovered humpback whale signals evaluated with Normalized Subband Envelope Correlation algorithm is 0.52±0.02.show less
- Feb.17,2025
- Chinese Optics Letters,Vol. 23, Issue 7
- (2025)
A concept for a femtosecond pulse compressor based on underdense plasma prisms is presented. An analytical model is developed to calculate the spectral phase incurred and the expected pulse comp
A concept for a femtosecond pulse compressor based on underdense plasma prisms is presented. An analytical model is developed to calculate the spectral phase incurred and the expected pulse compression. A 2D particle-in-cell simulation verifies the analytical model. Simulated intensities ($\sim10^{16}$ W/cm$^2$) were orders of magnitude higher than the damage threshold for conventional gratings used in chirped pulse amplification. Theoretical geometries for compact (10s cm scale) compressors for 1 PW, 10 PW, and 100 PW power levels are proposed.show less
- Feb.17,2025
- High Power Laser Science and Engineering
- Journal
- Feb. 13, 2025
- Journal
- Feb. 12, 2025