Polarization states of transmitted light in linear birefringence gratings

Polarization properties of gratings are used to develop new types of fiber Bragg grating (FBG)-based sensors. The evolutions of states of polarization (SOPs) of transmitted light in linear birefringence gratings were studied based on Jones matrix and coupled mode theory, and they were plotted on Poincare sphere. The effects of transmitted length, linear birefringence value and incident SOPs on PDL, the first normalized Stokes parameter and the evolutions of SOPs were discussed. The results show that the SOPs of transmitted light change with linear birefringence value and grating length, and the SOPs relative curves of different wavelengths spread gradually with the increasing grating lengths or birefringence values. The wavelength point of maximum amplitude of the first normalized Stokes parameter is the same as that of polarization-dependent loss, both increase monotonously with birefringence value, which could be used for sensor measurement.