Broadband 2D n × n Vortex Arrays Generated from an Efficient Petal‐Like Raman Laser with an Astigmatic Mode Convertor

Abstract

Broadband vortex arrays distributed in 2D n × n vortices are extremely needed for multiple microparticle manipulation, high‐capacity optical communication, and quantum information. Vortex arrays are usually generated with spatial light modulators, metamaterials; it is a big challenge to improve beam quality and output power. Herein, crisscross 2D n × n vortex arrays are converted from petal‐like Raman lasers with an astigmatic mode convertor. Efficient petal‐like lasers in the form of the Laguerre–Gaussian mode with zero radial index and l azimuthal index (LG0,l ) are irradiated in a Raman microchip laser (RML) by adjusting optimal beam waist and locating the position of focus spot of the annular pump beam. High‐beam‐quality LG0,9 petal‐like Raman laser oscillating at broadband wavelength (bandwidth: 16.2 nm) is generated with power of 773 mW and an efficiency of 10.6%. The conversion efficiency from petal‐like laser to crisscross vortex array is as high as 90%. The vortex array with 5 × 5 vortices operating around 1078 nm is generated with a power of 693 mW and an optical efficiency of 9.5%. Taking advantages of the broad emission spectrum of ytterbium‐doped laser materials and stimulated Raman scattering effect, RMLs are potential sources for generating flexible vortex arrays with desired 2D n × n vortices oscillating in Raman wavelengths.