Microspectrometer on a chip (MICROSPOC): first demonstration on a 320x240 LWIR HgCdTe focal plane array

Abstract

By measuring the spectral responses of infrared focal plane arrays (IRFPAs), one can extract at a given wavelength the cartography of the pixels responses, called the hyperspectral cartography. Recently, hyperspectral cartographies have been obtained from IRFPAs that exhibited small defects of substrate thickness. These defects produce Fizeau fringes across the FPA. By purposely amplifying this phenomenon during the process of realisation, one can easily generate a good approximation of a two-beam interferometer in the immediate neighbourhood of the FPA. Like a classic Michelson interferometer with tilted plane mirrors, this on-a-chip interferometer produces a spatially-modulated interferogram, the Fourier-transform of which yields the spectral content of the illuminating beam. A first prototype of this Fourier-transform microspectrometer on a chip (MICROSPOC) has been realised and tested. Experimental results will be presented and the potential of this approach will be discussed.