Optical Receiver Design Using Pyroelectric Detectors.

An optical receiver operable over a broad spectral range of the infrared region is possible using a pyroelectric point detector. The pyroelectric detector is modeled as a transducer of thermal radiation to an electrical signal cascaded with an R-C network. The pyroelectric signal is amplified by a preamplifier network. The sensor is, therefore, modeled as a linear bandpass filter. The preamplifier is configured in two modes, the voltage mode which limits the response to a narrow electrical bandwidth, and the current mode which broadens the response over a wide electrical bandwidth. The responsivity bandwidth product is dependent upon the preamplifier components determined by the mode of operation. However, pulse widths and pulse repetition rates can be calculated without regard to mode of operation. The detector performance is theoretically limited by fluctuations of the incident radiation and is practically constrained by the thermally generated noise within the preamplifier components. The optical receiver signal processing consists of a whitening filter cascaded with a matched filter. The filter network is used to optimally process the sensor output. The processing scheme provides a signal-to-noise improvement of 1 million over straight detection. Author