Coupling characteristics of cladding modes in tilted optical fibre Bragg gratings

We have studied both theoretically and experimentally the effect of grating tilting on the coupling between fundamental core mode and cladding modes in an optical fibre Bragg grating. The coupling is shown to be very sensitive on the tilting angle. It has also shown that tilting angle has to be minimised in fibres with designs to suppress the coupling between fundamental core mode and cladding modes. We have also studied the single strong loss peak accompanying Bragg reflection peak in depressed cladding fibres, showing a good agreement between the measured and theoretically predicted behaviour