Abstract

The performance of IR lidar and heterodyne radiometry systems is generally limited by the sensitivity of a wideband IR detector or detector array operating in either the direct or heterodyne detection mode. Here a comparison of heterodyne and direct detection for remote sensing uses is briefly described, and important differences are pointed out. Some of the design considerations for high-performance wideband photodiodes and photoconductors are discussed, including sensitivity-bandwidth trade-offs and when preamplifier noise becomes a limiting factor. A survey of available direct and coherent detectors at 10.6 μm and other IR wavelengths is presented, which includes operating requirements and sensitivities of detectors with bandwidths in the 10–2000-MHz range and cut-off wavelengths in the 5–30-μm region. Various wideband photodiodes and photoconductors using group IV, III–V, and II–VI semiconductor materials are compared.

© 1987 Optical Society of America