Chapter 10 - Fiber Grating Devices in High-Performance Optical Communications Systems

Abstract

This chapter provides an overview and a technology update of the fiberoptic component technology known as fiber grating. This component is also often referred to as Fiber Bragg Grating (FBG), fiber phase grating, ultravoilet (UV)–induced fiber grating, or in–fiber grating. A fiber grating is a holographic diffraction grating written by UV light directly into the core of an optical fiber. It is a phase grating as it mainly comprised a periodic variation of the index of refraction. Once exposed, the grating is essentially permanent. Fiber gratings are considered as critical components for many applications in fiberoptic communications and sensor systems. Advantages of fiber gratings over competing technologies include all-fiber geometry, low insertion loss, high return loss or extinction, and potentially low cost. It is observed that fiber gratings can be made with minimal polarization dependence, passive temperature compensation, and extremely high reliability. The most distinguishing feature of fiber gratings is the flexibility it offers for achieving the desired spectral characteristics. The chapter also reviews the materials aspects of the major approaches to fiber grating fabrication. It also discusses properties of fiber gratings, device properties, and applications of fiber gratings.