Extremely Nondegenerate Two-photon Processes in Semiconductors

摘要

Direct-gap semiconductors show enhanced two-photon absorption and nonlinear refraction for the extremely non-degenerate case, i.e. for two light waves of very different wavelength, as compared to the degenerate case. We have verified this through measurements of non-degenerate two-photon absorption and nonlinear refraction in several direct-gap semiconductors. We have demonstrated application towards mid-infrared detection and imaging, as well as 2-photon gain in the mid infrared. We also show how semiconductor quantum wells may be employed to engineer even larger enhancements of these effects.