Third-order nonlinear optical properties of a π-conjugated phenoxazinium compound: Mechanism and dynamic response

The third-order nonlinear optical response of a novel phenoxazinium salt dissolved in acetonitrile was investigated using a modified time-resolved pump–probe measurement with phase object at 532 nm with pico-second laser pulse. The experimental results clearly indicate that the observed nonlinear response should be of excited-state origin. The compound exhibits strong reverse saturable absorption and self-focusing effects plus long excited-state lifetimes. The nonlinear absorptive and refractive parameters of the phenoxazinium salt were evaluated by combination of picosecond pump–probe measurements and nanosecond Z-Scan experiments. The experiment results demonstrate this compound is a promising nonlinear optical material.