In-fiber grating systems for pulse compression and complete dispersion compensation

An important application of in-fibre gratings is for dispersion compensation. Linearly chirped Bragg gratings used in reflection have a constant dispersion over bandwidths sufficient to support ultra-short pulses and so have particular potential in this area. Such gratings have been demonstrated in a variety of linear dispersion compensation applications. In this paper the authors look at using chirped gratings in two different applications which go beyond this simple linear dispersion, linear optical regime. In the first of these they use fibre nonlinearity and the linear dispersion of a linearly chirped grating to compress a pulse spectrally broadened by self-phase modulation. Both experimental and theoretical investigations have been carried out on this scheme. Such compression may find application for compressing solitons to reduce the fiber lengths required in photonic switching applications. The second application is to use quadratically chirped gratings to perform higher order dispersion compensation in the fiber. A simple group delay model for chirped in-fiber gratings has been used to derive design parameters for such a system; and the results compared with numerical simulations. Higher order dispersion compensation may find application in dispersion managed high bit rate communication systems or in ultrashort pulse modelocked fiber laser sources