Fiber-Bragg-Grating Based Optical Amplifiers

In this chapter, we propose several schemes for fiber amplifiers which are all using fiber Bragg gratings (FBGs) as the key elements for their advantages of better uniformity, higher contrast ratio and lower cost. Several applications using FBG-based fiber amplifiers are also introduced. Therefore, this chapter initiates the overview of FBGs characteristics in Sec. 1, then addresses the FBGs playing solo-function roles in the fiber amplifiers in Sec. 2. The examples are like gain equalizer, dispersion compensator, signal reflector, pump reflector and other purposes. Next, Sec. 3 addresses the FBGs playing multiple-function roles in the hybrid fiber amplifiers. It is based on the construction of a C-band erbium-doped fiber amplifier (EDFA) and an L-band Raman fiber amplifier (RFA). The serial type, parallel type, bridge type and bidirectional C + L band hybrid amplifiers using single-wavelength pump laser diodes are proposed. Dispersion management and gain equalization among the C+Lband channels are realized simultaneously. Pump reflectors and double-pass schemes are used to increase the slope efficiency. Signal power variation among the channels are reduced by varying the reflectivities of these corresponding FBGs. Sec. 4 deals with FBGbased optical network devices with built-in fiber amplifier. Such networks devices include the reconfigurable optical add-drop multiplexer (ROADM) either in unidirectional or bidirectional transmission scheme, and the optical cross-connect (OXC) device is also proposed. Power compensation are realized with a bulit-in fiber amplifier. After various kinds of FBG-based fiber amplifiers are discussed, we summarize this chapter and conclude their potential utilization within optical communications and optical sensing.