Intracavity second harmonic generation from a WSe2 monolayer in a passively mode-locked picosecond fiber laser

A single layer WSe2 crystal is transferred on the tip of a single mode fiber that is placed in the cavity of a Yb3+ doped picosecond fiber oscillator. This intracavity monolayer generates second harmonics without affecting the stable mode-locking and laser output of the fiber oscillator. This method utilizes the higher intracavity optical intensities to increase the SHG conversion efficiency, thus combining the high nonlinear susceptibility and the phase-matching independence of a monolayer with the versatility of a fiber laser in an all-fiber integrated system. We also demonstrated a procedure to verify the monolayer placement on the fiber core by hyperspectral mapping. This intracavity SHG has possible applications for self-referencing f-2f interferometry in fiber-laser frequency combs. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

A single layer WSe2 crystal was successfully used to generate second harmonics in a fiber laser without affecting its performance, demonstrating a new approach for all-fiber integrated systems. Verification of the monolayer placement on the fiber core was achieved through hyperspectral mapping. This technique has potential applications for self-referencing f-2f interferometry in fiber-laser frequency combs.