Nonlinear terahertz Kerr effect in quasi-2D MnPS3

Quadratic electro-optic effect (Kerr effect) is shown to be efficiently induced by THz electric field in quasi-two-dimensional (2D) material MnPS3. The waveform of the THz induced response practically follows the intensity of the employed nearly single cycle THz pulse. While neither THz-induced absorption nor linear electro-optical effect were observed, we demonstrate that the THz electric field induces the refraction coefficient anisotropy experienced by light at the wavelength of 800 nm. In our experiment, the anisotropy results in polarization rotation of the light and corresponds to the nonlinear refractive index of the sample about of 13.1×10-14 W-1‧cm2. This promotes the quasi-2D MnPS3 as a promising candidate for practical application in future ultrafast electro-optical devices.