  The longwave infrared (LWIR) region of the spectrum spans 8 to 14 {\mu}m and
enables high-performance sensing and imaging for detection, ranging, and
monitoring. Chip-scale integrated LWIR photonics has enormous potential for
real-time environmental monitoring, explosive detection, and biomedicine.
However, realizing advanced technologies such as precision sensors and
broadband frequency combs requires ultra low-loss components, which have so far
remained elusive in this regime. We demonstrate that non-epitaxial germanium is
an enabling technology for longwave infrared integrated photonics, using it to
demonstrate the first high quality (Q) factor whispering gallery mode
microresonators in the LWIR, which we couple to integrated low-loss waveguides.
At 8 {\mu}m, we measure losses of 0.5 dB/cm and intrinsic Q factors of
2.5x10^5, nearly two orders of magnitude higher than prior LWIR resonators. Our
work portends the development of integrated sensing and nonlinear photonics in
the LWIR regime.
