Broad band p-Ge optical amplifier of terahertz radiation

A solid state broad band amplifier of terahertz radiation (1.5-4 THz), base d on intersubband transitions of hot holes in p-Ge is demonstrated. The gai n is investigated as a function of applied magnetic and electric fields by transmission measurements using a laser system with two p-Ge active crystal s, when one operates as an oscillator and one as an amplifier. A peak gain higher than usually reported for p-Ge lasers has been achieved using time s eparated excitation of the oscillator and amplifier. Distinct differences i n gain dependence on applied fields are noted between low- and high-frequen cy modes of p-Ge laser operation. (C) 1999 American Institute of Physics. [ S0021-8979(99)04718-0].