Measurement of Mueller matrix for an optical fiber system with birefringence and polarization-dependent loss or gain

In an optical fiber system with both birefringence and polarization-dependent loss or gain (PDL/G), a set of input polarization states and their corresponding outputs are deduced to fulfill some general relationships in Stokes space, by considering the fact that the Mueller matrix of such an optical fiber system meets Lorentz transformation. Then, it can be proven that the minimum number of input polarization states is three for an explicit determination of such a Mueller matrix and no independent input parameter is redundant. Based on the theoretical findings, a general and simple approach is proposed to measure the Mueller matrix. The requirements regarding the choices of three inputs are presented for achieving optimum measurement stability and accuracy. Experimental results on an optical fiber system, formed by two 10-km long single-mode fibers with an optical isolator in between, show excellent agreement with the theory.