Wide-band Fabry-Perot-like filters in optical fibre

An important component in optical systems which has to date been difficult to produce in a format compatible with optical fibre systems is the Fabry-Perot (FP) resonator. Although narrow-band devices have been reported with very high finesse, for applications in short pulse lasers and high speed communication system a response over several nanometres or more is required. The primary problem preventing the fabrication of wide-band filters using unchirped Bragg gratings written in photosensitive optical fibre is that the limited Δn which may be achieved without loss limits the bandwidth of the device. In this paper we demonstrate a method to produce Fabry-Perot-like structures in which the bandwidth is limited primarily by the range of chirp that can be produced in the grating