Integrated polarimeters based on anisotropic photodetectors

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Abstract
Anisotropic detectors (AD's) can be designed by coating a photosensitive surface (e.g., Si) with a birefringent thin film whose principal axes are in the plane of the film. An integrated polarimeter (IP) is described that uses four linear photodetectors, of which three are AD's. The light beam, whose Stokes parameters (SP's) are to be measured, is relayed from one detector to the next by near-normal-incidence partial specular reflection while remaining in one plane. By a suitable choice of surface properties and orientations of the AD's, the four output electrical signals of the four detectors determine completely and unambiguously all four SP's. This IP with AD's (IPAD) has all the advantages of the previously described four-detector polarimeter [Opt. Lett. 10, 309 (1985)]. In addition, the IPAD offers a compact design with small-area detectors.