Nonlinear Optical Absorption Properties of Sputtered WSe2 Thin-films in the Near-Infrared Spectral Band

Abstract

We present a detailed investigation on the intensity dependent third-order nonlinear optical (NLO) properties of RF-sputtered WSe₂ thin film using ultra short pulses. The investigation employed a single-beam Z-scan technique using near-infrared (NIR) ultra short pulses centered at 1030 nm for ascertaining the NLO response. The results reveal a reverse saturable absorption (RSA) signature, which is primarily due to the contribution from two-photon absorption (TPA). We explored the impact of high optical fluence on the TPA process and observed the weakening of the nonlinear optical absorption in WSe₂ thin film, which essentially pointed towards a significant contribution of free-carriers as well as band-filling effect. This research elucidates the insight of photophysical properties of WSe₂ thin films and shows the potential use as optical limiters.