Tunable absorptive nonlinearities of silver-modified few-layer black phosphorous nanocomposites

Abstract

Layered black phosphorus (BP) has broad optoelectronics and photonics applications in photodetectors, photovoltaics, ultrafast laser generation, etc. In this work, we report the manipulation of nonlinear absorption by doping metal Ag ions in few-layer black phosphorous (F-BP). F-BP nanosheets were synthesized by ultrasonic method, and then silver-modified F-BP (Ag/F-BP) nanocomposites were prepared by chemical synthesis method. The as-synthesized nanocomposites were characterized by means of X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, and UV–vis–IR spectrophotometry. The nonlinear absorption effects of nanocomposites were investigated by performing the Z-scan measurements with femtosecond laser pulses at the wavelength of 800 nm. The results show that the nonlinear absorption effect can be changed from saturable absorption (SA) to two-photon absorption (TPA) by doping Ag in F-BP nanosheets. Moreover, with the increase of low-dose Ag content, the TPA effect of Ag/F-BP nanocomposites has been greatly enhanced. The corresponding physical mechanism was discussed. This metal-ion modulated 2D nanomaterial with tunable optical nonlinearity has the great potential in nonlinear optoelectronic devices.