Prediction of polarisation behaviour of twisted optical fibres containing Bragg grating sensors

A new theoretical method is presented for the prediction of the polarisatio n behaviour of a twisted single mode optical fibre containing Bragg grating sensor, which is treated as a series of polarisation wave plates. The bire fringence induced by UV irradiation during the sensor fabrication and that caused by twisting of the fibre and Bragg grating are considered. The numer ic calculations have been carried out for Cc-doped silica single mode fibre s containing Bragg gratings. The simulated results of circular birefringenc e for twisted single mode optical fibres are In agreement with previous kno wn theoretical results. Influencing factors under investigation are the pos ition of the grating, the UV irradiation induced birefringence, addition of single mode fibre segments, and the initial polarisation states of the inc ident light.