All-Fiber Vortex Laser Based on a Nonlinear Amplifying Loop Mirror and a Coupler

We constructed an all-fiber pulsed vortex laser based on a nonlinear amplifying loop mirror (NALM) and a coupler that was fused with a single-mode fiber (SMF) and a few-mode fiber (FMF). The cavity, including an NALM, was in charge of the generation of pulses. The coupler inserted into the cavity acted as a mode converter. The produced 393-fs vortex beam had a spectrum width of 12 nm and centered at 1567 nm.