Suppression of cladding mode coupling in Bragggrating using Ge ₂ O-B ₂ O ₃ codoped photosensitive claddingoptical fibre

Abstract

A new type of photosensitive optical fibre codoped with Ge2O-B2O3 in both the core and cladding has been fabricated for applications in Bragg gratings. Coupling of the fundamental core mode into the cladding modes was suppressed with a narrow 3 dB bandwidth in the Bragg grating. An increase in photosensitivity was also achieved by using high reflectivity Bragg gratings imprinted without the need for any hydrogen treatment.