Nonlinear optical response spatial self-phase modulation in MoTe: correlations between χ and mobility or effective mass.

We report on an unambiguous observation of the third-order nonlinear optical effect, spatial self-phase modulation (SSPM), in a MoTe dispersion. The values of the third-order nonlinear optical coefficients effectively for one-layer MoTe, χone-layer(3), are obtained through the SSPM method at excitation wavelengths 473, 532, 750, and 801 nm, respectively. The wind-chime model is used to explain the ring formation time. The wavelength dependence of χone-layer(3) compares well with the photo-absorption spectra. Significantly, we find a correlation between χ and the carrier mobility μ or effective mass m*, which again further supports the laser-induced ac electron coherence in 2D materials.