Neutron transmutation doped Thz p-Ge laser

Amplified terahertz radiation (1.5 - 4.2 THz, 70 - 200 micron) in p-Ge is generated on transitions between light- and heavy-hole sub-bands in crossed electric and magnetic fields. Population inversion builds for certain E/B ratios, when light holes accumulate on closed trajectories below the optical phonon energy, while heavy holes scatter on optical phonons. Traditional p-Ge lasers output up to 10 W for cm/sup 3/ active volume and microsecond pulse duration. The saturation intensity within the active crystal can reach kW/cm/sup 2/, but such is unachievable at the output because of low gain. This is caused in part by the inhomogeneous doping of the melt-grown germanium traditionally used.