Basic Elements of Optical Communication

An optical communication system transmits analog and digital information from one place to another using high carrier frequencies lying in the range of 100—1000 THz in the visible and near‐infrared region of the electromagnetic spectrum. This chapter describes the basic elements of the optical communication channel, including the transmitter, as a source of light, and the receiver, as the detector of light. The photodetectors do not affect the propagation properties of the optical wave but certainly must be compatible with the rest of the system. The transmitter includes a modulator, a driver, a light source, and optics. The receiver includes optics, a filter, a polarizer, a detector, a trans‐impedance amplifier, a clock recovery unit, and a decision device. The atmospheric channel attenuates the power of the optical signal and widens and spreads it in the spatial, temporal, angular, and polarization domains.