title: Generation of doughnutlike vortex beam with tunable orbital angular momentum from lasers with controlled Hermite-Gaussian modes.
abstract: This study demonstrates successive higher-order Hermite-Gaussian (HG(0,m)) mode operations in a microchip solid-state laser with a controlled off-axis laser diode (LD) pumping and generation of the corresponding doughnutlike laser beam of tunable ring diameter and orbital angular momentum, by experimentally focusing a Hermite-Gaussian mode (HGM) lasing beam into an astigmatic mode converter (AMC) with a mode-matching lens. Based on the successful generation of stable doughnutlike vortex beams by combining the LD off-axis pumping of microchip lasers and an AMC, this study proposes a design for a compact, solid doughnutlike vortex laser beam generator that combines three elements (i.e., laser cavity, mode-matching lens, and AMC) into one practical device. The desired doughnutlike vortex beam with different orbital angular momentum is easily generated by simply controlling the lateral off-axis pump position and pump beam shape on the laser crystal by numerical simulation.
authors.affiliation: Department of Physics, National Cheng Kung University, Tainan City, Taiwan. scchu@mail.ncku.edu.tw
authors.forename: Shu-Chun
authors.initials: SC
authors.lastname: Chu
authors.forename: Takayuki
authors.initials: T
authors.lastname: Ohtomo
authors.forename: Kenju
authors.initials: K
authors.lastname: Otsuka
mesh_terms: D003198:Computer Simulation; D003460:Crystallization; D004867:Equipment Design; D007834:Lasers; D008027:Light; D015233:Models, Statistical; D016011:Normal Distribution; D055095:Optics and Photonics; D012107:Research Design; D012542:Scattering, Radiation