Attempt to amplify broadband THz radiation with a p-Ge active crystal

Although amplification of terahertz (THz) radiation have been highly desired to have a more intense THz radiation source, it was never achieved so far. The reason for it is the lack of efficient and broadband THz laser gain media. In other words, if we can use an efficient, broadband THz laser, it is possible to amplify the THz pulsed radiation due to the stimulated emission induced when the THz radiation travels though the laser gain medium. At present, the p-type Ge laser seems to be the only candidate which is feasible to be used as the THz amplifier: The p-Ge laser uses the population inversion between the light holes and heavy holes in the valence band, and has a broadband gain typically over 1-4 THz range and a relatively high peak power output from mW to W level. Therefore, a p-Ge laser can be used as an amplifier for the broadband THz pulsed radiation. In this paper we report our attempt to amplify THz radiation pulses with a p-type Ge active medium