Nonlinear absorption and nonlinear refraction in a chemical vapor deposition-grown, ultrathin hexagonal boron nitride film

An ultrathin hexagonal boron nitride film is synthesized by a method of chemical vapor deposition. Irradiated by femtosecond laser pulses in the visible spectrum of 400800 nm, it exhibits multiphoton absorption and positive nonlinear refraction properties. The two-photon and three-photon absorption coefficients are of the order of 10(-5) cm W-1 and 10(-14) cm(3) W-2, respectively. The nonlinear refraction coefficient is as large as similar to 10(-8) cm(2) W-1. These nonlinear coefficients lead to figures of merit that meet the material requirements for all-optical switching devices. (C) 2016 Optical Society of America