Measurement of the temperature dependence of midinfrared optical absorption spectra of germanium in intense laser fields

摘要

We have investigated the temperature dependence of midinfrared optical absorption in germanium under intense free-electron laser fields. We observed that the absorption decreases as temperature decreases. We find that the temperature dependence of the absorption is consistent with calculations based on the Keldysh theory, in which the temperature dependence of the direct-gap energy of germanium is considered.