All-fiber passively Q-switched laser with flat-top beam emissions

Flat-top beams have plenty of applications in theoretical and applied research, hut they are not eigenmodes of the wave equation. Here, we propose an effective strategy for generating flat-top beams in fibers, which originates from the incoherent superposition of orbital angular momentum (OAM) and fundamental (LP01) modes. The designed all-fiber passively Q-switched laser can realize high-quality pulsed flat-top and OAM beam emissions. The normalized root mean square of the flat-top beam is around 4.7%, and the purity of the OAM mode is calculated to be higher than 98%. For the first time to the best of our knowledge, pulsed emission of a flat-top beam is achieved using an all-fiber laser. Moreover, its repetition rate and duration can be controlled by adjusting the pump. (C) 2022 Optica Publishing Group

Automated summary

This paper proposes an effective strategy for generating flat-top beams in fibers, achieving high-quality pulsed flat-top and OAM beam emissions.