Intensity-dependent nonlinear refraction of antimonene dispersions in the visible and near-infrared region.

Antimonene is a stable 2D allotrope of antimony that is predicted to have a direct bandgap, high third-order optical nonlinear susceptibility, and high electron mobility. These properties give it huge potential applications in photonics and optoelectronics. However, the nonlinear refractive response of antimonene dispersions, which is the key to nonlinear refraction-based devices, has not been fully investigated. In this work, we investigated the optical nonlinearities of the antimonene dispersions by spatial self-phase modulation (SSPM) at 405, 785, and 1064 nm wavelengths. The SSPM rings were observed at 405, 785, and 1064 nm, implying the broadband nonlinear optical response of antimonene dispersions from visible to near-infrared. The effective nonlinear refractive index, n(2), and the third-order susceptibility, chi((3)), of the antimonene dispersion were measured to be similar to 10(-5) cm(2) W-1 and similar to 10(-8) esu, respectively. Furthermore, the nonlinearity of antimonene was demonstrated to be tuneable by the laser intensities. The relative change of the nonlinear refractive index, Delta n(2e)/n(2e), was observed to range from 14% to 63% for different intensities. Our results will be helpful for the photonic applications of antimonene in a broadband wavelength range, such as optical modulators and switchers. (C) 2018 Optical Society of America