Tunable far-infrared solid-state lasers based on hot holes in germanium

The basic principles for achieving population inversion and stimulated emission in the far-infrared fromp-Ge are discussed. In the heavy-light hole lasing mode a broad gain region is found resulting in a broad multimode spectrum due to intracavity modes. By attaching external plates of germanium a single mode operation is realized. The obtained powers are in the W range with linewidths of ≈0.2 cm−1. A single mode magnetically tunable coherent source is achieved with the light hole cyclotron resonance laser. With external mirrors a tuning range from 20 to 120cm−1 with magnetic fields between 1 and 6 T is achieved. The intensity of the single mode is in the order of W, the linewidth below 0.2 cm−1.