Dual-band QWIP focal plane array for the second and third atmospheric windows

We report on the development and status of a dual-band QWIP FPA with 384 × 288 pixels and 40 μm pitch for the 3-5 μm (mid-wavelength infrared, MWIR) and 8-12 μm (long-wavelength infrared, LWIR) spectral bands. The array is based on a photovoltaic “low-noise” QWIP for the LWIR and a photoconductive QWIP for the MWIR and allows for simultaneous integration of both bands on each pixel. Array histograms indicate a noise-equivalent temperature difference as low as 17 mK for the MWIR band and 43 mK for the LWIR band at an integration time of 7.6 ms. In addition, we have investigated test devices with different gratings, geometries, and sizes and discuss some tradeoffs for dual-band diffraction gratings.