An ultracompact device, designed with two air-etched trenches embedded in two opposite corners of a silicon bus waveguide, for generation and (de)multiplexing optical orbital angular momentum (OAM) modes is proposed. The double-trench waveguide can generate OAM_±1 and OAM_±2 modes when the phase difference of two rotated orthogonal LP-like modes is equal to π/2 (or 3π/2). The operating principle and mode purity of the generated OAM modes are theoretically and systematically investigated. The simulation results show that the average purities of OAM_±1 modes exceed 90%, and that of OAM_±2 modes is greater than 80% over a wide wavelength range of 1.4–1.625 µm. Furthermore, an on-chip five-OAM-mode (de)multiplexer (OAM₀, OAM_±1, OAM_±2) with a compact footprint of <200×4×4 µm³ is designed, whose main mode crosstalk is less than −20 dB. The presented OAM mode generator and (de)multiplexer are promising for applications like optical communications and quantum information processing.

提出了一种超紧凑器件，该器件设计有两个嵌入硅总线波导的两个相对角的空气蚀刻沟槽，用于产生和（去）复用光学轨道角动量（OAM）模式。当两个旋转正交的类LP模式的相位差等于π/2（或3π/2）时，双沟道波导可以产生OAM _±1和OAM _±2模式。理论和系统地研究了生成的 OAM 模式的工作原理和模式纯度。仿真结果表明，在1.4-1.625 µm 的宽波长范围内，OAM _±1模的平均纯度超过 90%，OAM _{±2模的平均纯度超过 80%。}此外，片上五 OAM 模式（解）复用器（OAM ₀, OAM _±1 , OAM _±2 ) 设计紧凑，占位面积<200×4×4 µm ³，其主模串扰小于-20 dB。所提出的 OAM 模式发生器和（解）复用器有望用于光通信和量子信息处理等应用。