Nonlinear Coherent Light–Matter Interaction in 2D MoSe₂ Nanoflakes for All‐Optical Switching and Logic Applications

Abstract A strong nonlinear optical response of 2D MoSe₂ nanoflakes (NFs) through spatial self‐phase modulation (SSPM) and cross‐phase modulation (XPM) induced by nonlocal coherent light–matter interactions is reported. The coherent interaction of light and MoSe₂ NFs creates the SSPM of laser beams, forming concentric diffraction rings. The nonlinear refractive index (n₂) and third‐order broadband nonlinear optical susceptibility (χ⁽³⁾) of MoSe₂ NFs are determined from the self‐diffraction pattern at different exciting wavelengths of 405, 532, and 671 nm with varying laser intensity. The evolution and deformation of diffraction ring patterns are observed and analyzed by the “wind‐chime” model and thermal effect. By taking advantage of the reverse saturated absorption of 2D SnS₂ NFs compared to MoSe₂, an all‐optical diode has been designed with MoSe₂/SnS₂ hybrid structure to demonstrate the nonreciprocal light propagation. Few other optical devices based on MoSe₂ and semiconducting materials such as Bi₂Se₃, CuPc, and graphene have been investigated. The all‐optical logic gates and all‐optical information conversion have been demonstrated through the XPM technique using two laser beams. The proposed optical scheme based on MoSe₂ NFs has been demonstrated as a potential candidate for all‐optical nonlinear photonic devices such as all‐optical diodes and all‐optical switches.