Direct evidence for the role of streaming motion in the hot-hole p-Ge laser
To date the role of streaming motion in hot-hole p-Ge lasers has been inferred only through theoretical considerations; in this paper we present experimental proof of the importance of streaming motion for p-Ge lasers. We have performed magnetoabsorption measurements in p-Ge under intense crossed electric and magnetic fields. Observation of the change of a magneto-optical resonance from loss (absorption) to gain with increasing electric field has enabled us to identify directly the high-field lasing transition for the first time. It is confirmed to be the light-hole b-set n=1-0 transition in the coupled band model. By analysing emission data obtained with stressed laser crystals we suggest impurity-related cyclotron resonance transitions to be involved in the lasing process for high-concentration samples.