Miniaturization of p -Ge lasers: Progress toward continuous wave operation

We have observed intervalence band laser action in Al-doped germanium crystals with volumes as small as 0.03 cm3, one order of magnitude smaller than previously studied p-Ge laser crystals. A duty cycle of 1.5×10−4 was achieved. We show evidence that crystal heating plays a key role in the duration of the emission pulse and have measured a maximum pulse length of 11 μs for a 0.43 cm3, Ga-doped germanium crystal. Such progress in the understanding and performance of p-Ge hot hole lasers marks a significant step toward continuous wave operation.