Thermal effects in widely tunable germanium terahertz lasers

We report laser emission from Be-doped Ge lasers at high repetition rates of up to 45 kHz which is one order of magnitude higher than previously reported. Laser radiation was detected from Ge:Be crystals with volumes as small as 0.5 mm3 and with intercontact distances down to 1 mm. We present a thermal analysis and derive the design parameters for continuous wave Ge lasers.