Large second-harmonic vortex beam generation with quasi-nonlinear spin-orbit interaction

• 作者: Wenchao Zhao Kai Wang Xuanmiao Hong Bingxia Wang Xiaobo Han Kun Wang Weiwei Liu Hua Long Bing Wang Peixiang Lu
• 来源期刊: 科学通报（英文版）
• 年，卷（期）: 2021,（5）
• 所属期刊栏目: ARTICLES
• 页码范围: 449-456
• 页数: 8页
• 语种: 英文

摘要

A harmonic vortex beam is a typical vector beam with a helical wavefront at harmonic frequencies (e.g.,second and third harmonics).It provides an additional degree of freedom beyond spin-and orbitalangular momentum,which may greatly increase the capacity for communicating and encoding information.However,conventional harmonic vortex beam generators suffer from complex designs and a low nonlinear conversion efficiency.Here,we propose and experimentally demonstrate the generation of a large second-harmonic (SH) vortex beam with quasi-nonlinear spin-orbit interaction (SOI).High-quality SH vortex beams with large topological charges up to 28 are realized experimentally.This indicated that the quasi-angular-momentum of a plasmonic spiral phase plate at the excitation wavelength (topological charge,q) could be imprinted on the harmonic signals from the attached WS2 monolayer.The generated harmonic vortex beam has a topological charge of In =2nq (n is the harmonic order).The results may open new avenues for generating harmonic optical vortices for optical communications and enables novel multi-functional hybrid metasurface devices to manipulate harmonic beams.