Quantum well infrared photodetectors and thermal imaging cameras

We report on our QWIP focal plane array (FPA) developments for thermal-imaging applications in the 8 - 12 µm long-wavelength infrared (LWIR) and 3 - 5 µm mid-wavelength infrared (MWIR) regimes. Photovoltaic low-noise QWIP FPAs are best suited for long integration times (> 20 ms), resulting in the best noise-equivalent temperature difference (NETD) ever achieved with any detector technology. For short integration times, we use photoconductive QWIP arrays with higher carrier concentrations and quantum efficiency, with an NETD below 50 mK at only 2 ms integration time for FPAs with 24 µm pitch. For the MWIR, we have developed FPAs based on strained InGaAS/AIGaAs quantum wells. These 640 x 512 MWIR QWIP FPAs exhibit a high peak quantum efficiency above 10% and an excellent NETD of 14 mK at 88 K detector temperature. High-performance FPAs for the MWIR can thus be realized with GaAs technology.