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.