Generation of spatially unpolarized light by a Cornu depolarizer: equator polarization states as type II unpolarized light

Abstract

We demonstrate the generation of spatially unpolarized light by exploiting a quartz Cornu depolarizer. Linearly polarized light impinging on the depolarizer is spatially polarization-dispersed, and the output polarization state is analyzed by a Schaefer-Collett or Berry-Gabrielse-Livingston polarimeter and a CCD camera or a photo detector, respectively. The ensemble of the observed spatially resolved normalized Stokes parameters s1(x, y), s2(x, y), s3(x, y) and the spatially resolved degree of polarization DOP(x, y) together with their counterparts spatially integrated over the beam profile show that the full beam is in fact spatially unpolarized light. The light consists of a spatial superposition of the manifold of all purely linearly polarized states encompassing completely the equator of the Poincaré sphere, thus so-called equator states. The accompanying invariance under the influence of a half-wave plate suggests that this is type II unpolarized light.