Mode structure of the p-germanium far-infrared laser with and without external mirrors: Single line operation

Abstract

The mode structure of p-Ge far-infrared lasers with and without mirrors is investigated. Without external mirrors a multimode spectrum is observed and quantitatively explained in terms of waveguidelike modes. An external resonator drastically reduces the number of oscillating modes. For the first time single line operation is demonstrated in this configuration.

Tunable cyclotron-resonance laser in germanium

“…The peak power of the stimulated CR emission is of the same order of magnitude as that of the interband emission which was estimated earlier by comparison with a FIR gas laser to be about 500 mW. 7 In Fig. 2 the emission is shown as a function of the magnetic field detected with the Ge:Ga detector for sample 1 with external mirrors (dashed curve) and for comparison without external mirrors (solid curve).…”

“…The spectrum of this emission is broadband. 6,7 The higher-field range (3 T < B < 4 T) corresponds to stimulated cyclotron-resonance emission (see also spectra in Fig. 3).…”

Far-infrared p-Ge laser with variable length cavity

“…No special mirror adjustments were performed during the cavity length tuning, and mirror alignment accuracy was defined only by the mechanical parts with an uncertainty of order 1 degree. This experiment demonstrates a high degree of laser cavity stability, which was not similarly tested in previous closed semi-confocal cavity experiments with p-Ge lasers [7,8].…”

“…Such electrodynamic cavities are very sensitive to the degree of parallelness of the opposite crystal faces. Some effort was made to improve stability by implementing curved mirrors on the back surfaces of transparent spacers, which were similarly placed in contact with crystal end faces [7,8]. A fundamental problem with all of these closed cavity schemes is that tunability of the laser frequency is allowed only by hopping between laser modes, which are rigidly determined by the dimensions of the active crystal and other solid cavity components [5].…”

Single axial-mode selection in a far-infrared p-Ge laser

“…Operation on magnetic-field tunable cyclotron-resonance lines 1 and use of intracavity frequency selection [2][3][4][5] have made considerable progress toward this goal. However, single axial-mode generation, although suggested, 2 has not been demonstrated until now.…”