Measuring Stokes parameters by means of unitary operations

We propose an improved scheme to measure the Stokes polarization parameters by making the to-be-measured state evolve unitarily. An optical setup able to implement the scheme is presented theoretically and experimentally. Theoretical results indicate that at least two unitary operators should be employed to determine the Stokes parameters of light with arbitrary degrees of polarization. Compared with the results acquired by a commercial polarimeter, the proposed scheme is used to obtain the Stokes parameters of 13 representative states with degrees of polarization r = 1 and r = 0.5, experimentally. The fidelity between the two states gained by the above methods is in the range of 0.9802 +/- 0.0046 to 1.0000 +/- 0.0000. (C) 2021 Optical Society of America