Patent ID: 6941081

Claim:
A method of polarization measurement, comprising: (a) directing an optical signal characterized by a polarization state into a polarization controller, said polarization controller consisting of a half-wave plate followed by a quarter-wave plate each characterized by respective orientations; (b) directing the optical signal from the polarization controller into a polarizer; (c) directing the optical signal from the polarizer to a wavelength dispersive element to generate a dispersed optical signal comprising a plurality of spectral components each characterized by a wavelength range; (d) directing the dispersed optical signal into a photo-detector for detecting the plurality of spectral components; (e) setting the polarization controller to at least four different positions; wherein the first of the at least four different positions corresponds to setting the half-wave plate orientation and the quarter-wave plate orientation to be the same as an orientation of the polarizer; the second of the at least four different positions corresponds to setting the half-wave plate orientation at about 22.5 angular degrees with respect to the orientation of the polarizer, and setting the quarter-wave plate orientation to be the same as the orientation of the polarizer; the third of the at least four different positions corresponds to setting the half-wave plate orientation at about 45 angular degrees with respect to the orientation of the polarizer, and setting the quarter-wave plate orientation to be the same as the orientation of the polarizer; and the fourth of the at least four different positions corresponds to setting the half-wave plate orientation at about 22.5 angular degrees and the quarter-wave plate orientation at about 45 angular degrees with respect to the orientation of the polarizer; (f) for each of the plurality of positions of the polarization controller, measuring the power of the optical signal using the photo-detector; and (g) obtaining the polarization state of the optical signal by analyzing the powers of the optical signal measured in (f).