Strong optical limiting behavior discovered in black phosphorus

Black phosphorous (BP), the most thermodynamically stable allotrope of phosphorus, fills up the lacuna left by other two-dimensional materials with a band gap from 0.3 to 2 eV. The narrow direct band gap and the strong light-matter interaction make BP a promising nonlinear optical (NLO) nano-material. In this paper, the NLO properties of multilayer BP nano-sheets were researched by an open aperture z-scan method. Optical limiting (OL) behavior was observed in the BP material. Three different excitation wavelengths (1064, 532 and 355 nm) were used in the experiments, and the long wavelength excitation exhibited superior NLO performance, including OL and saturable absorption (SA). Our results demonstrate that BP is a promising candidate for OL applications.