Pulse buildup of the germanium far-infrared laser

We study the dynamics of an electrically pumped p-Ge laser with frequency fixed to 100 cm−1 by a novel selective cavity. The growing laser power increases the pump current long before it reaches a saturating power level, an effect explained by photoionization. We further find that the laser pulse can be delayed or even quenched by injected off-resonance far-infrared radiation. This effect not only gives a gain coefficient of 0.01 cm−1 and a saturation power of 400 W−which confirms the high-power capability of the laser−but furthermore reveals a novel quasihomogeneous broadening of the gain spectrum caused by transit-time effects of rapidly moving holes.