Chapter 8 - Optical signal processing

Abstract

The nonlinear effects occurring inside optical fibers can be used to make useful devices capable of processing high-speed optical signals. Stimulated Raman scattering, for example, can be used for making Raman amplifiers that are often used for amplifying optical signals in modern WDM systems. Similarly, four-wave mixing can be used to make fiber-optic parametric amplifiers. This chapter focuses on a variety of signal-processing devices that make use of the nonlinear effects such as self-phase modulation, cross-phase modulation, and our-wave mixing. Section 8.1 deals with wavelength converters that change the wavelength of a WDM channel without affecting its contents. The time-domain switches in which individual bits, or packets of bits, belonging to a specific channel are switched to a different port are described in Section 8.2. Applications of such switches for optical time-domain demultiplexing and format conversion are discussed in Section 8.3. Optical regenerators, devices that are used for reshaping and retiming of optical pulses belonging to an optical bit stream, are covered in Section 8.4.