All-fiber short-pulse vortex laser with adjustable pulse width

A laser with short pulse width and direct output of a vortex beam was reported herein. This laser was fabricated from a nonlinear loop mirror (NOLM) and a coupler composed of a single mode fiber and few-mode fiber fused together. The NOLM is responsible for generating pulses, and the coupler acts as a beam splitter and mode converter. Two stable vortex modes can be formed by adjusting the polarization controller, whose pulse widths are 1.098 ps and 542 fs, respectively. (paper)