Polarization Evolution of a Vector Optical Field in a PT Symmetry System

The evolution of a vector optical field (VOF) with a spiral phase and azimuthally-variant polarization distributions in the field cross-section in a Parity-Time (PT) symmetric system is demonstrated. The evolutions of the Stokes parameters of azimuthally-variant VOF in PT symmetry system are obtained by the split-step finite-difference method. Numerical results show that the coherent superposition of two orthogonal polarization components leads to the occurrence of the linear-circular polarization conversions in the periphery of the VOF during propagation in a PT symmetric system. Moreover, the optical intensity and the circular polarization components generated by transmission is not uniform during propagation in a PT symmetric system due to the gain and loss effect of PT symmetry. These results provide a new approach for the manipulation of a VOF with different modulation factors ( refractive index, gain/loss, and lattice period) at different propagation distances in the PT symmetric system.