Liquid‐Exfoliated Few‐Layer InSe Nanosheets for Broadband Nonlinear All‐Optical Applications

Abstract The nonlinear optical response of 2D materials has attracted wide attention in the recent year due to their strong nonlinearity and broadband characteristics. A new optical scheme is presented enabling the implementation of the broadband nonlinear optical response and their all‐optical applications of few‐layered InSe nanosheets. First, few‐layer InSe nanosheets are synthesized by using the liquid‐phase exfoliated method; then the third‐order nonlinear susceptibility is measured with the spatial self‐phase modulation. Based on the obtained nonlinear optical response, a method is proposed for forming a nonreciprocal propagation photonic diode based on a mixed structure of InSe/C 3 N 4 . In addition, through the cross‐phase modulation of the two beams, the all‐optical switches and all‐optical information conversion have also been discussed. The implementations of these few‐layered InSe‐based all‐optical devices show that the layered InSe is indeed an excellent candidate for use in future all‐optical photonic circuits as an optical diode and optical switching.