Coherence and transient nonlinearity in laser probing

Iam Choon Khoo, Ping Zhou, Liang Yu +1 more

The dynamics of the transient thermal-grating-mediated probe-beam amplification effect in a nematic liquid crystal film is studied with the use of millisecond laser pulses. These experimental observations and the accompanying transient multiwave mixing analysis show that peak probe gain can occur at various locations within the grating decay time; the higher the induced index change, the sooner will peak gain occur.>

BERNARD SHORE

Xiaoqin Li, Yanwen Wu, Xiaodong Xu +2 more

Transient differential transmission measurements were performed to study coherent dynamics involving the biexciton resonance confined in a single $\mathrm{GaAs}$ quantum dot. When laser pulses with sufficient bandwidth were tuned to cover both the exciton and biexciton transitions, an oscillatory behavior in the probe transmission was observed. These oscillations persist only as long as the pump and probe pulses overlap in time, in contrast to the usual quantum beat phenomena.

Xiao Yan Cheng

I. C. Khoo, P. Zhou, R. R. Michael +2 more

We present a detailed general theory of multiwave mixing effects in a nonlinear medium produced by two incident coherent laser beams. Calculations are performed for localized as well as diffusive types of nonlinearities. The theory accounts for all the relevant parameters such as laser pulse widths, medium response times, nonlinearities, interaction length, intensities, beam ratio, phase modulation effects, losses, and side diffractions. The interrelationship between two- and multiwave mixing effects and the evolution of transient to stationary behavior is explicitly worked out. In particular, the gain experienced by a weak incident probe beam via these mixing effects is quantitatively analyzed as a function of the aforementioned parameters.

V. Ernst