Abstract

Recent progress in microfabrication technology increases the prospects for realizing very-low-power nonlinear optical devices with strong-light-field confinement. To design such devices, we need to examine nonlinear processes at the weak-excitation limit. In ZnSe we found a power region in which the nonlinear phase shift showed third-order responses even at the exciton resonance.¹ There, we can apply perturbational techniques. Thus we can follow the nonlinear optical processes, showing the change of the quantum-mechanical states of the media step by step. For the third-order nonlinearity near exciton resonance, the relevant states are the ground state, the one-exciton state, and the two-exciton state. We call such techniques elementary excitation.

© 1993 Optical Society of America