The authors would like to thank Yeun-ho Choi, Erick Michel, Jedon Kim, Jaejin Lee, Joseph Wojowski, Hooman Mohseni, Di Wu, Brett Lane, and Yajun Wei for their contribution to this work. The research at the Center for Quantum Devices and that presented here were supported by the U.S. Air Force (Gail Brown, William Mitchel, Daniel Johnstone), the U.S. Army (Henry Everitt), the Office of Naval Research (Yoon-Soo Park), and the Defense Advanced Research Projects Agency (L. N. Durvasula, Ray Balcerak).

Figure 7.19: Absolute spectral responsivity of a device with ? _c = 16 ?m. The 90% to 10% cutoff energy width is about 12 meV. The absorption features of CO ₂ and H ₂O are due to the small difference in the optical pathlength of the background measurement and the detector measurement.