ABSTRACT

A transmitter and a receiver are the most fundamental devices to construct lightwave transmission systems. A transmitter consists of electronic circuits, a driving amplifier, and a light source. The transmitter converts the electrical input signal into the optical output signal. Light sources are semiconductor lasers and light emitting diodes. A combination of a laser and a modulator or a modulator-integrated semiconductor laser is also used as a light source. A receiver consists of a photo-detector, followed by electrical pre- and postamplifiers and electronic circuits. A semiconductor photo-diode or an avalanche-photo-diode is used as a photo-detector. The receiver converts the input optical signal into the output electrical signal. A most simple point-to-point optical link can be realized by connecting a transmitter and a receiver through optical fibers. A repeater consists of a receiver followed by a transmitter. The repeater converts the input optical signal to the output optical signal. Inside the repeater, the optical signal is amplified, reshaped, and regenerated.