High-order mode Yb-doped fiber lasers based on mode-selective couplers

We experimentally investigate high-order modes (HOMs) generating at the wavelength of 1.0 mu m in all-fiber Yb-doped lasers based on mode-selective couplers (MSCs). Broadband MSCs for HOMs conversion are achieved by optimizing the phase-matching condition at 1.0 mu m. Efficient generation of HOMs is demonstrated with the MSCs inserted both into continuous-wave and mode-locked fiber lasers. The slope efficiencies of HOMs (LP11 LP02 and LP21) are presented and discussed. Additionally. cylindrical vector and orbital angular momentum beams are produced out of the MSCs by controlling the polarization states. The results show proof-of-concept implementation of the MSCs, which enables high efficiency of HOMs generation especially in pulsed fiber lasers and holds promising applications in laser material processing. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement