Enhanced nonlinear optical response in GeSe-based multilayer structure

GeSe, an emerging two-dimensional material, exhibits a significant potential in nonlinear optics. This study explores an effective method to enhance the nonlinear optical properties of GeSe through the utilization of a multilayer film structure. We designed and fabricated a (SiO2/ZnSe/GeSe/ZnSe)4/SiO2 multilayer film structure, which substantially augments the nonlinear optical response of GeSe via electric field enhancement and transmission spectrum edge modulation. Z-scan measurements reveal that the two-photon absorption coefficient and nonlinear refractive index of the multilayer film reach 25.616×104 cm/GW and 8.235×10−13 m2/W, representing more than a fourfold increase compared to a single GeSe film. A further analysis of optical limiting characteristics reveals onset and optical limiting thresholds of 0.043 and 0.711 GW/cm2, respectively. This multilayer film design strategy significantly enhances the nonlinear optical performance of GeSe, offering possibilities for developing high-efficiency optical modulators and optical switches based on two-dimensional materials.