ABSTRACT

Following the presentation of optical modulation in the direct and external modulation in Chapter 5, this chapter presents advanced modulation formats of light wave sources via external modulators. This is an extension of the modulation employing optical modulatorsconnected at the output of acontinuous-wave (CW) laser source. The laser is thus turned on at all times and the generated optical CWs are then modulated in terms of frequency,phase, and/or amplitude through an external optical modulator. Hence, the pulse sequence that envelops the carrier phase or frequency underneath can be varied according to the modulation schemes. The uses of these transmitters in optical communication transmissionsystems are given, especially those for long-haul transmissions at avery high bit rate. MATLAB® Simulink® models are described for generation of advanced modulation format in the optical domain.