Author Affiliations
Abstract
1 Terahertz Technology Innovation Research Institute, Terahertz Spectrum and Imaging Technology Cooperative Innovation Center, Shanghai Key Laboratory of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093, China
2 Shanghai Institute of Intelligent Science and Technology, Tongji University, Shanghai 200092, China
3 Department of Physics, Lomonosov Moscow State University, Moscow 119991, Russia
4 e-mail: ymzhu@usst.edu.cn
The investigation of converged twisted beams with a helical phase structure has a remarkable impact on both fundamental physics and practical applications. Geometric metasurfaces consisting of individually orientated metal/dielectric meta-atoms provide an ultracompact platform for generating converged vortices. However, it is still challenging to simultaneously focus left-handed and right-handed circularly polarized incident beams with pure geometric phase modulation, which hinders the independent operation on topological charges between these two helical components. Here we propose and experimentally demonstrate an approach to design terahertz geometric metasurfaces that can generate helicity-independent converged vortices with homogeneous polarization states by the superposition of two orthogonal helical vortices with identical topological charges. Furthermore, the multiplexing of polarization-rotatable multiple vortices in multiple dimensions, i.e., in both longitudinal and transverse directions, and a vortex with an extended focal depth is confirmed by embedding polarization modulation into the geometric metasurfaces. The demonstrated approach provides a new way to simultaneously manipulate orthogonal helical components and expand the design dimension, enabling new applications of geometric metasurface devices in polarization optics, twisted-beam related image and edge detection, high capacity optical communication, and quantum information processing, to name a few.
Photonics Research
2022, 10(6): 06001517
Author Affiliations
Abstract
A compact monolithic Nd:YAG non-planar ring laser with diffusion-bonded Cr4+:YAG is demonstrated, and high stable pulsed single-frequency laser at 1.06 \mu m is realized. Theoretical analysis and simulation results of pulsed laser parameters are illustrated. 14.96-kW maximum peak power, pulse-width of 4.8 ns is achieved for single-frequency operation.
140.3540 Lasers, Q-switched 140.3560 Lasers, ring 140.3570 Lasers, single-mode Chinese Optics Letters
2014, 12(2): 021404
根据高稳定性半导体激光(LD)泵浦单块非平面环形腔(NPRO)单频激光器对于功率稳定性和频率稳定性的要求, 设计并研制了一套高精度的精密温控系统。该系统基于模拟比例-积分-微分(PID)控制原理, 采用程控调节P和PI的方式, 通过对半导体制冷器(TEC)的驱动控制, 实现在-10~+70℃范围内对LD和NPRO单块晶体温度的精确控制, 控温精度达±0.01℃。采用该温控系统的LD泵浦1645nm NPRO单频激光器, 30min内相对波长稳定性达8.32×10-7。
单频激光器 精密温控 波长稳定性 single frequency lasers PID PID accurate temperature control wavelength stability