Uncooled Focal Plane Array for Multiband IR Imaging Using Optical-Readout Bimaterial Cantilevers

This paper presents the design, fabrication, and performance of a 256 × 256 multiband infrared (IR) focal plane array (FPA) using microbimaterial cantilever as the sensitive pixel. Different from traditional uncooled IR FPA that works only at long wavelength IR, the working bandwidth of the presented FPA is extended to full band IR, covering the three IR atmospheric windows of 1-2.5 μm, 3-5 μm and 8-14 μm simultaneously. The multiband performance is attributed to the elaborately designed multiband absorber consisting of a stacked layer of silicon nitride, chromium nanofilm, and gold mirror. The absorbing mechanism of the stacked layer is discussed in detail and testified by experimental results. Images of short-wavelength, middle-wavelength, and long-wavelength IR were captured successfully with the single FPA. The measured sensitivity and noise equivalent temperature difference of the FPA are 0.18 μm/K and 194.7 mK, respectively.