An infrared passively Q-switched laser based on graphene/BN heterojunction

Abstract

Passively Q-switched solid-state lasers (PQSL) can obtain output lasers with narrow pulse widths and high peak powers, where play a vital role in the information society. Saturable absorbers (SA) are an essential part of passively Q-switched solid-state lasers. In this paper, we demonstrated 2 μm passively Q-switched (PQS) solid-state laser based on a graphene/BN heterojunction saturable absorber. In the experiments, we used two output mirrors with transmittance of 1.5 %/2.5 % for comparative study. We also used monolayer graphene as saturable absorber for experiment to compared with graphene/BN saturable absorber. The experimental results showed that the best passively Q-switched operation was achieved with the graphene/BN heterojunction saturable absorber at output mirror transmittance of 1.5 %. When the maximum absorption pump power was 1.49 W, the maximum average output power was 38 mW, corresponding with a slope efficiency of 5.4 %. At this point, the minimum pulse width was 1.56 μs, corresponding with a repetition frequency of 52 kHz. The single pulse energy and the peak power were calculated to be 730.36 nJ and 466.96 mW, respectively. The center wavelength of the PQS laser was 2066.8 nm. The experimental results showed that graphene/BN heterojunction was a promise saturable absorber in the field of 2 μm passively Q-switched solid-state lasers.