Synthesis, Green Photoluminescence and Studies of Nonlinear Optical Spatial Self Phase Modulation Effect in 2D Ga₂Te₃ Nanosheets

Abstract

The liquid-phase exfoliation (LPE) technique has been employed to prepare two-dimensional (2D) gallium telluride (Ga 2 Te 3 ) nanosheets with an average thickness of ∼2.4 nm and linear optical properties, including UV−visible absorption and photoluminescence (PL) emission characteristics of the sample in the green wavelength region are reported. The third-order nonlinear optical (NLO) responses of the colloidal suspension of 2D Ga 2 Te 3 are determined at 532 and 632 nm wavelengths by a spatial self-phase modulation (SSPM) experiment. The value of the third-order NLO refraction coefficient (n 2e ) and effective susceptibility for monolayer (χ (3) Mono ) 2D Ga 2 Te 3 under 532 (632) nm continuous wave (CW) excitation is extracted to be 2.60 × 10 −7 (0.32 × 10 −7 ) cm 2 /W and 1.12 × 10 −9 (1.37 × 10 −10 ) e.s.u., respectively. The origin of the observed SSPM patterns under 532 nm excitation was elucidated theoretically. Finally, the correlation of χ (3) Mono with the mobility of charge carriers for a vast number of 2D materials is utilized to establish the origin of the observed NLO effect under 532 nm pump laser radiation in the 2D Ga 2 Te 3 . Additionally, NLO absorption coefficients of 2D Ga 2 Te 3 have been extracted using the femtosecond Z-scan technique at 800 nm. We observed a switching behavior (saturable to threephoton absorption) in the nonlinear absorption mechanism with different input peak intensities. The highest three-photon absorption coefficient of ∼1.68 cm 3 /GW 2 was observed for a 350 GW/cm 2 peak intensity. We believe that such reports of interesting linear and NLO properties of this newly synthesized 2D material can be utilized in the future for a wide number of optoelectronic applications.