Transient gain of the germanium hot hole laser

The small-signal amplification of a far-infrared p-Ge laser is measured with a gas laser and a fast detector, and is found to be surprisingly large (≈0.1 cm -1 ) and short-lived (≈0.2 μs), suggesting further ways to optimize this laser. Absorption by impurity and Drude processes is also observed. Saturation effects during self-oscillation indicate that neutral impurities are involved in the laser process.