All-fiber orbital angular momentum (OAM) amplifier with high purity and broadband spectrum gain based on a fused taper vortex-beam coupler (VBC) has been studied. Active and passive few-mode fibers ...

In this letter, we demonstrate a high performance fused-type mode selective coupler that couples the LP/sub 11/ mode in one fiber and the LP/sub 01/ mode in another using highly elliptical core ...