Spatial-mode switchable ring fiber laser based on low mode-crosstalk all-fiber mode MUX/DEMUX

We report an all-fiber ring laser that emits linearly polarized (LP) modes based on the intracavity all-fiber mode multiplexer/demuttiplexer (MUX/DEMUX), Multiple LP modes in ring fiber laser are generated by taking advantage of mode MUX/DEMUX. The all-fiber mode MUX/DEMUX are composed of cascaded mode-selective couplers (MSCs). The output lasing mode of the ring fiber laser can be switched among the three lowest-order LP modes by employing combination of a mode MUX and a simple N x 1 optical switch. The slope efficiencies, optical spectra and mode profiles are measured. (C) 2017 Elsevier Ltd. All rights reserved.