Bilayer Bismuth Selenide nanoplatelets based saturable absorber for ultra-short pulse generation (Invited)

Abstract

Based on an efficient and bottom-up synthesis technique, Bismuth Selenide (Bi2Se3) nanoplatelets with uniform morphology and average thickness down to 3–7nm had been fabricated. Its nonlinear absorption property under high power excitation had been well characterized by our Z-scan measurement system at different illumination wavelengths, and we found that the as-fabricated bi-layer Bi2Se3 nanoplatelets show unique nonlinear optical responses, that is, with a saturable optical intensity of 32GW/cm2 (resp. 3.7MW/cm2 ) and a modulation depth of 88% (resp. 36%) at 800nm (resp. 1565nm). By implementing its saturable absorption property, we designed an optical saturable absorber device based on bilayer Bi2Se3 nanoplatelets through deposited them onto the end-facet of optical fiber. The as-fabricated optical saturable absorber device allows for the generation of mode-locking pulses at 1571nm with pulse duration of 579fs and a repetition rate of 12.54MHz at a pump power of 160mW. The method on fabricating ultrathin Bi2Se3 nanoplatelets may pave a new way to massive production of large-area topological insulator thin films that can be used in two-dimensional layered materials related photonics device.