A Miniaturized Polymer Grating for Topological Order Detection of Cylindrical Vector Beams

Polarization topological order of a cylindrical vector beam (CVB) can be defined as the repetition number of 360 degrees polarization state change along the azimuthal axis, with its sign denoting the rotating direction of the polarization. In order to detect CVBs with different order, a miniaturized polymer grating is proposed and demonstrated. The grating is almost pure phase modulated and polarization independent. The CVB modes with different orders or with the same order but opposite sign can easily be separated by adding a quarter wave plate and a polarizer. The experimental results are consistent with the theoretical predictions, thus validating our proposed method.