Transmitter design

Abstract

This chapter gives a detailed overview of how optical high-order modulation signals are generated. It describes transmitters for the generation of optical ASK-signals, DPSK-signals and QAM-signals and considers star-shaped and square-shaped QAM constellations (Star QAM and Square QAM). Since all the transmitters are composed of fundamental key components (laser, modulators, pulse carver), the functionality of these components is discussed at the beginning of this chapter. The subsequent description of the different transmitters includes optical transmitter parts as well as electrical parts. It contains much detailed information such as the concrete assembly of the coders and level-generators. The quality of the transmitter output signals has a critical influence on the overall system performance. Therefore the electrical field for the optical output signals is analytically derived for all transmitters shown, and differences in signal characteristics, symbol transitions and chirp behavior are emphasized. This helps us understand the system behavior of the transmitters discussed later on in Chap.7. © 2009 Springer-Verlag Berlin Heidelberg.