Birefringence distribution mapping in optical fibers with a coherent polarization-OTDR

We propose a new Polarization-OTDR system to measure the distribution of birefringence. The evolution of state of polarization(SOP) is detected utilizing the coherent Rayleigh scattering light in two fibers (Reference fiber and fiber under test). The birefringence is calculated based on Jones matrix, and the trace of Jones matrix can describe the magnitude of birefringence. The resolution and SNR of coherent Polarization-OTDR is significantly improved.