Third-order nonlinear properties and reverse absorption behavior in layered Ti3C2 MXene in the near infrared region

Abstract

Two-dimensional transition metal carbides/nitrides (MXenes) have attracted a lot of attention as optical materials owing to their unique electronic and optical features. In this paper, we demonstrated the nonlinear optical response of Ti3C2 MXene in the near infrared (NIR) regime at 1 and 1.3 µm. The nonlinear optical absorption behavior was systematically studied by the open/closed aperture (OA/CA) Z-scan techniques. Under a low excitation intensity, the saturable absorption dominated the optical nonlinear process, and the maximum effective nonlinear absorption coefficients βeff were −0.59 cm/MW and −0.68 cm/MW at 1 and 1.3 µm, respectively. The nonlinear refractive index n2 and the third-order susceptibility of Ti3C2 Mxene at 1 µm were −2.18 ×10−2 cm2/GW and 3.65×10−3 esu, respectively. While with the excitation laser at 1.3 µm, the nonlinear refractive index n2 was −1.64×10−2 cm2/GW and the third-order susceptibility was 2.75×10−3 esu. With the increase of incident optical intensity, the two-photon absorption (TPA) process was observed, leading to the reverse absorption phenomenon. Our results confirmed that Ti3C2 MXene possessed intensity-depended nonlinear optical properties, which could be applied in various nonlinear optical devices.