Pulse duration dependent optical nonlinearities of Bi2Se3 thin films

Abstract

Topological insulators, such as the Bi2Se3 material, exhibit significant optical nonlinearities. This work investigates the impact of the pulse duration on the nonlinear optical responses of Bi2Se3 layers. Scanning electron microscopy studies have been performed to reveal the crystalline structure of the samples. The nonlinear optical performance has been investigated for a wide range of pulse durations, from 400 fs to 10 ps, using 1030 nm laser excitation. The nonlinear absorption coefficients recorded in this study range from -1.45 x10−7 m/W to -4.86 x10−7 m/W. The influence of two different mechanisms on optical nonlinearities was observed and discussed. Identical experimental conditions have been employed throughout the studies allowing a direct comparison of the results.