Visible optical nonlinearity of vanadium dioxide dispersions.

Vanadium dioxide (VO 2 ), a correlated oxide compound, is one of the functional materials extensively studied in solid state physics due to its attractive physical properties. However, the nonlinear optical response of VO 2 and related all-optical applications have been paid less attention. Here, the nonlinear refractive index ( n 2 ) and third-order nonlinear susceptibility ( χ (3) ) of VO 2 dispersions have been acquired to be 3.06 × 10 -6 cm 2 W -1 and 1.68 × 10 -4 esu at a wavelength of 671 nm, and 5.17 × 10 -6 cm 2 W -1 and 2.83 × 10 -4 esu at a wavelength of 532 nm via the spatial self-phase modulation (SSPM) and spatial cross-phase modulation (SXPM) effects in the visible regime, respectively. Based on the excellent nonlinear optical properties of VO 2 dispersions, the proof-of-principle functions such as optical logic or-gates, all-optical switches, and inter-channel information transfer are implemented in the visible wavelength. The experimental results on the response time of VO 2 to light indicate that the formation of diffraction rings is mainly an electronically coherent third-order nonlinear optical process. The experimental results show that the VO 2 dispersions exhibit an excellent nonlinear optical response and may lay the foundation for the application of VO 2 -based all-optical devices.