Dual band QWIP MWIR/LWIR focal plane array test results

We report on the results of laboratory and field tests on a pixel-registered, 2-color MWIR/LWIR 256x256 QWIP FPA with simultaneous integrating capability. The FPA studied contained stacked QWIP structures with spectral peaks at 5.1 mum and 9.0 mum. Normally incident radiation was coupled into the devices using a diffraction grating designed to operate in both spectral bands. Each pixel is connected to the read-out integrated circuit by three bumps to permit the application of separate bias levels to each QWIP stack and allow simultaneous integration of the signal current in each band. We found the FPA to have high pixel operability, well balanced response, good imaging performance, high optical fill factor, and low spectral crosstalk. We present data on measurements of the noise-equivalent temperature difference of the FPA in both bands as functions of temperature and bias. The FPA data are compared to single-pixel data taken on devices from the same wafer. We also present data on the sensitivity of this FPA to polarized light. It is found that the LWIR portion of the device is very sensitive to the direction of polarization of the incident light. The MWIR part of the device is relatively insensitive to the polarization. In addition, imagery was taken with this FPA of military targets in the field Image fusion techniques were applied to the resulting images.