Surface fluorination treated indium-based quantum dots as a nonlinear saturable absorber for a passive Q-switched 1.0 μm laser

Abstract

InP-based quantum dots (QDs) have attracted considerable interest in the optoelectronic field owing to their favorable properties. However, to date, the nonlinear optical properties and ultrafast photonics applications of InP-based QDs have rarely been explored. In this study, InP/ZnSe/ZnS QDs with surface fluorination treatment (InP-HF) have been fabricated. Consequently, the nonlinear saturable absorption properties of such InP-HF QDs with surface modification are explored by realizing a modulation depth of 3.27% and a saturable intensity of 1.10 MW cm⁻². We report on the passive Q-switching of a diode-pumped Nd:YVO₄ near-infrared laser at 1064 nm (∼1.0 μm) using InP-HF QDs as a SA. At this wavelength, the threshold of pump power is as low as 1 W, and the maximum average output power and the shortest pulse widths are 2.5 W and 178 ns, respectively. The laser results suggest that surface fluorination treated InP-HF QDs could be very promising for generating ultrashort pulse visible lasers.