Mid-infrared properties of optical parametric oscillations based on layered PtS2 modulated laser pumping

Abstract

In recent years, layered transition metal sulfides (TMDCs) exhibit excellent nonlinear saturable absorption properties in laser modulations. Nevertheless, few of them are applied to the optimization of optical parametric oscillators (OPOs). In this work, we prepared a 12.5 nm-thickness platinum disulfide (PtS2) saturable absorber (SA) by a combination of electron beam evaporation (EBE) and post-vulcanization method. The nonlinear transmittance is measured, which exhibits the SA characteristic of PtS2 film. The acousto-optic (AO) Q-switch and the prepared PtS2 SA are used to realize the operation of active and passive Q-switched OPO, and the mid-infrared idler pulse with nanosecond width is obtained. By measuring the experimental output results, the optimizations of PtS2 SA to OPO's operation are analyzed, including the stabilization of pulse train by 240%, the compression of idler-light pulse by 59.7%, the improvement of peak power by 198%. As a result, the improvement of nonlinear conversion is attained by 16.9%. The phenomenon may be due to the excellent saturable absorption effect of PtS2 SA to the fundamental light. This paper shows the optimization effect of the prepared layered transition metal sulfide for laser intracavity modulation on the nonlinear frequency conversion process, especially for the improve of nonlinear conversion effect.