Optical Receivers

In an optical communication system, the photodetector can be configured either as a direct or incoherent detector, or as a coherent detector. To obtain the best possible photoreceiver performance, the parameters of both the photodetector and the preamplifier should be optimized. Therefore, this chapter concentrates on describing some important photodetector structures and optical receivers. It describes photodetectors without internal gain, such as pn photodiodes, pin photodetectors (pin-PDs), Schottky barrier photodetectors, and metal–semiconductor–metal photodetectors (MSM-PDs). The chapter also describes photodetectors with internal gain, like avalanche photodetectors (APDs), photoconductive photodetectors, and phototransistors. Then, it describes some advanced photodetectors, such as resonant cavity-enhanced photodetectors (RCE-PDs) and waveguide photodetectors (WG-PDs). The chapter also describes noise sources in photodetection systems as well as optical detection system architectures.