Dynamic optical nonlinearities are investigated with a dual-beam (pulsed-pump, cw probe) Z-scan technique. Monitoring of probe transmission after strong pump excitation permits determination of time-varying parameters such as nonlinear refraction n(I, t) and absorption α(I, t). Continuous time resolution provides an efficient means of measuring and distinguishing fast and slow nonlinear mechanisms such as electronic, free-carrier, and thermal effects observed in semiconductors. We demonstrate this technique in CdTe and measure bound-electronic refraction; two-photon absorption; free-carrier refraction, absorption, and diffusion; thermal refraction and temperature changes; and related time constants.
© 1996 Optical Society of America
David O. Caplan, Gregory S. Kanter, and Prem Kumar, "Characterization of dynamic optical nonlinearities by continuous time-resolved Z-scan," Opt. Lett. 21, 1342-1344 (1996)