MXenes, a new class of 2D transition metal carbides, nitrides, and carbonitrides, have attracted much attention due to their outstanding properties. Here, we report the broadband spatial self-phase modulation of Ti 2 CT x MXene nanosheets dispersed in deionized water in the visible to near-infrared regime, highlighting the broadband nonlinear optical (NLO) response of Ti 2 CT x MXene. Using ultrafast pulsed laser excitation, the nonlinear refractive index n 2 and the thirdorder nonlinear susceptibility χ 3 ð Þ monolayer of Ti 2 CT x MXene were measured to be $10 −13 m 2 /W and $ 10 −10 esu, respectively. Leveraging the large optical nonlinearity of Ti 2 CT x MXene, an all-optical modulator in the visible regime was fabricated based on the spatial cross-phase modulation effect. This work suggests that 2D MXenes are ideal broadband NLO materials with excellent prospects in NLO applications.
K E Y W O R D S2D materials, all-optical modulator, MXene, spatial cross-phase modulation, spatial self-phase modulation # These authors contribute equally to the work.