Turn-key compact high temperature terahertz quantum cascade lasers: imaging and room temperature detection.

Terahertz quantum cascade lasers have been investigated as a turn-key terahertz source for widespread applications. Two lasers were mounted in a small liquid nitrogen-cooled dewar and combined with a sophisticated pulse driver. We present a detailed analysis in respect to current-voltage characteristics, emission wavelengths, polarization, pulse lengths and repetition rates. We have measured the laser power with a germanium photoconductor and compared the results to a Golay detector evaluating potential artifacts. We have studied mode profiles in the far-field which mirror the internal mode structure. Potential applications have been illustrated by imaging optical elements and a simple test object. Video rate room temperature imaging has been demonstrated in concept.