Tunable narrowband laser that operates on interband transitions of hot holes in germanium

Intraresonator frequency selection has made it possible to compress to 0.02 cm−1 the output spectral line of a laser working on interband transitions of holes in Ge. This laser operates in the long-wavelength IR region (50–140 cm−1). There is a considerable increase in the spectral power density of the line. We demonstrate the possibility of tuning the output frequency over a wide spectral region. We discuss the frequency-competition processes occurring in the active medium.