Two-color corrugated quantum well infrared photodetectors for remote temperature sensing

Multi-color infrared detection is an important function of thermal imaging since it can be used to acquire the temperature profile of an object. Quantum well infrared photodetectors (QWIPs), because of their tunability in terms of both detection wavelength and spectral lineshape, are uniquely qualified for this application. However, the realization of multi-color detection in a 2D staring array format has been impeded by the difficulties in simultaneously coupling light into different wavelength regions. Conventional coupling schemes, such as diffraction gratings, have been shown to be inadequate for this purpose, due to the fact that their coupling efficiency is wavelength dependent. In view of these problems, we proposed a new light coupling geometry for QWIPs, which we dubbed the corrugated QWIP (C-QWIP). The coupling efficiency of this new structure has been demonstrated to be independent of wavelength, and is thus qualified as a candidate for multi-color detection (Chen et al, Appl. Phys. Lett. vol. 68, p. 1446, 1996, and vol. 71, p. 3045, 1997). In this work, we report the fabrication of a two-color C-QWlP and the experimental results of tests of its ability for remote temperature sensing.