Dispersions of two-photon and three-photon absorption in GaS films from 540 to 1600 nm

【摘要】 The development of nonlinear optical materials with strong multiphoton absorption （MPA） is crucial for the design of ultrafast nonlinear optical devices,such as optical limiters and all-optical switchers.In this study,we present the wavelengthdependent coefficients of two-photon absorption （2PA） and three-photon absorption （3PA） in a Ga S film across a broad range of wavelengths from 540 to 1600 nm.The observed dispersions in the 2PA and 3PA coefficients align well with the widely used two-band approximation model applied to direct bandgap semiconductors.Notably,the Ga S film exhibits exceptional MPA properties with a maximum 2PA coefficient of 19.89 cm/GW at 620 nm and a maximum 3PA coefficient of4.88 cm³/GW²at 1500 nm.The Ga S film surpasses those found in traditional wide-bandgap semiconductors like β-Ga₂O₃,Ga N,Zn O,and Zn S while remaining comparable to monolayer Mo S₂,Cs Pb Br₃,and （C₄H₉NH₃）₂Pb Br₄perovskites.By employing a simplified two-energy-level model analysis,our results indicate that these large MPA coefficients are primarily determined by the remarkable absorption cross sections,which are approximately 4.82×10^-52·cm⁴·s·photon^-1at 620 nm for 2PAand 8.17×10^-80·cm⁶·s²·photon^-2at 1500 nm for 3PA.Our findings demonstrate significant potential for utilizing Ga S films in nonlinear optical applications.更多还原

【Abstract】 The development of nonlinear optical materials with strong multiphoton absorption （MPA） is crucial for the design of ultrafast nonlinear optical devices,such as optical limiters and all-optical switchers.In this study,we present the wavelengthdependent coefficients of two-photon absorption （2PA） and three-photon absorption （3PA） in a Ga S film across a broad range of wavelengths from 540 to 1600 nm.The observed dispersions in the 2PA and 3PA coefficients align well with the widely used two-band approximation model applied to direct bandgap semiconductors.Notably,the Ga S film exhibits exceptional MPA properties with a maximum 2PA coefficient of 19.89 cm/GW at 620 nm and a maximum 3PA coefficient of4.88 cm³/GW²at 1500 nm.The Ga S film surpasses those found in traditional wide-bandgap semiconductors like β-Ga₂O₃,Ga N,Zn O,and Zn S while remaining comparable to monolayer Mo S₂,Cs Pb Br₃,and （C₄H₉NH₃）₂Pb Br₄perovskites.By employing a simplified two-energy-level model analysis,our results indicate that these large MPA coefficients are primarily determined by the remarkable absorption cross sections,which are approximately 4.82×10^-52·cm⁴·s·photon^-1at 620 nm for 2PA and 8.17×10^-80·cm⁶·s²·photon^-2at 1500 nm for 3PA.Our findings demonstrate significant potential for utilizing Ga S films in nonlinear optical applications.更多还原