Nonlinear optical properties of solgel-derived glasses doped with copper selenide nanoparticles

Abstract

Transient differential absorption spectra of solgel glasses that contain copper selenide nanoparticles (NP’s) have been studied with a picosecond pump–probe technique. Oxidation of copper selenide NP’s results in the appearance of an additional absorption band peaked at ∼1 µm, which can be transiently bleached under laser excitation. Excited-state absorption related to mid-gap surface trap states was observed. The absorption recovery time was found to be ∼300 ps. The intensity-dependent transmission of oxidized copper selenide NP’s in solgel glass at 1.08 µm has been measured. Permanent laser-induced absorption changes in the glasses were studied with nanosecond pulses as a function of laser exposure. Passive Q switching of 1.06-µm Nd3+:Y3Al5O12, 1.34-µm Nd3+:YAlO3, and 1.54-µm Er3+: glass lasers has been realized with the glasses containing copper selenide NP’s used as saturable absorbers. Q-switched pulses with 100-ns (1.06 µm), 90-ns (1.34 µm), and 60-ns (1.54 µm) pulse widths were obtained.