Far infrared p-Ge laser: transition identification and evidence for streaming motion

C. R. Pidgeon, B. Murdin, C. Kremser, K. Unterrainer, E. Gornik

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Crossed electric and magnetic fields applied to p-Ge crystals can lead to stimulated FIR emission between different light hole Landau levels. 'Streaming motion' of heavy holes, where they repeatedly accelerate collissionless to the optical phonon energy and scatter back to the origin [1] is thought to be one of the main processes underlying the so-called p-Ge cyclotron resonance (CR) laser. The finite probability for heavy holes to scatter into light hole Landau levels (LL's) leads in this way to an increase of the population of light hole LL's (pumping mechanism). A population inversion between different LL's is built up due to the depopulation of low lying LL's by ionised impurity scattering [2] or due to mixing between light and heavy hole states {3], which, because of streaming motion of the heavy holes, leads to a reduction of the lower LL lifetime. To date the role of streaming motion in hot hole p-Ge lasers has been inferred only through theoretical considerations [3,4]; in this work we present the first experimental proof of the importance of streaming motion. We have performed magneto-absorption measurements in p-Ge under intense crossed electric and magnetic fields. The broadening of the observed cyclotron transitions and the disappearance of some of these transitions with increasing electric field is attributed to streaming motion. In addition, the observation of the change of a magnetooptical resonance from loss (absorption) to gain with increasing electric field has enabled us to identify directly the high field lasing transition. It is confirmed to be the light hole b-set n=1 to 0 transition in the coupled band model. The stimulated emission obtained in single line (linewidth of < 0.2cm-1) and linearly tuneable with magnetic field from 25 to 85 cm-1, with an estimated output power of 200 mW in a 1µs pulse.

Original languageEnglish
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
Volume2104
Publication statusPublished - 1993
EventProceedings of the 18th International Conference on Infrared and Millimeter Waves - Colchester, Engl
Duration: 6 Sep 199310 Sep 1993

Conference

ConferenceProceedings of the 18th International Conference on Infrared and Millimeter Waves
CityColchester, Engl
Period6/09/9310/09/93

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    Pidgeon, C. R., Murdin, B., Kremser, C., Unterrainer, K., & Gornik, E. (1993). Far infrared p-Ge laser: transition identification and evidence for streaming motion. In Proceedings of SPIE - The International Society for Optical Engineering (Vol. 2104)