Replication of phase-shifted DFB grating structures in photosensitive germania and rare-earth-doped optical fibres

In this paper we show that a variety of band-pass filters may be fabricated with ease using simple replication of phase-shifted phase-masks, in germania and rare-earth doped fibres. it is shown that the band-pass may be located anywhere within the band-stop of the grating by adjusting the phase-mask prior to writing. Phase-steps have also been introduced by “trimming” with UV radiation, one half of the length of the grating. Preliminary experiments shown that higher reflectivity gratings should allow lasing in rare earth doped fibres