Since the late 1990s, steady advances in wavelength division multiplexing (WDM) technology have provided better ways to increase the capacity of optical networks. Three significant trends become evident in long-haul transmission system, namely the continual increase in the number of dense WDM channels, the increase in data rates from 2.5 Gb/s to today's 10 Gb/s, to tomorrow's 40 Gb/s, and finally longer distances between electrical regeneration sites. These trends towards an increased optical network capacity are now clashing with chromatic dispersion. This paper will discuss the application of high-end FBGs to telecommunication systems, focusing on their performances with respect to chromatic dispersion. Two types of components will be discussed: low-dispersion FBG WDM filters and FBG dispersion compensators. High-quality ultra-low dispersion FBGs have been fabricated successfully and their key attributes will be discussed. Advanced applications of FBGs for chromatic dispersion compensation, such as broadband multi-channel dispersion and slope compensation, will be covered. In particular, FBG dispersion slope compensators can be used in conjunction with Dispersion Compensating Fiber (DCF) to fully manage the dispersion over a large number of WDM channels. The need for tunable dispersion compensation at 40 Gb/s transmission rates will be discussed. Experimental results will also be presented.