Accurate Evaluation Nonlinear Absorption Coefficients for Light Propagation in InAs, InSb, and HgCdTe Alloys (Preprint).

摘要

We present a full-bandstructure calculation of temperature- and wavelength-dependent two-photon absorption (TPA) coefficients and free-carrier absorption (FCA) cross sections in InAs, InSb, Hg1-xCdxTe alloys. Although the wavelength dependence of the TPA coefficients agrees well with widely used analytical expression, our calculated values are smaller by a factor of 1.2 to 2.5. In addition, the TPA coefficient depends sensitively on the photoexcited carrier density in small gap materials. The FCA is found to be due predominantly to holes. The FCA cross section is independent of the carrier density, but strongly dependent on the temperature. The calculated coefficients and lifetimes are fitted to closed-form expressions and used in solving the rate equations to obtain the transmitted pump and probe intensities as functions of incident intensity and sample thickness. The calculated pump transmission and time-dependent probe transmission in InAs agree very well with the measured values.