Spatial depolarization patterns generated with dynamic retardance functions

In this work we demonstrate a proof-of-concept depolarization emulator that generates customized spatial patterns of the polarization state (SoP) and degree of polarization (DoP). It is based on a pixelated LCOS-SLM addressed with a spatially time-varying retardance function. Three different cases featuring spatial control of the DoP are realized to show the potential of the method, including a spirally-shaped depolarization pattern. The polarization properties of the output light beam are verified by imaging the SLM screen onto a polarizing camera and performing Mueller matrix imaging polarimetry. We obtain the time-averaged Mueller matrix of the SLM and show that the output effective polarization state is governed by the averaged retardance, while the degree of polarization is governed by the retardance semidifference. An intuitive explanation of this performance is provided in the Poincaré sphere. The proposed technique could be useful in testing imaging polarimeters, in laser beam manipulation and in biomedical imaging, where emulating depolarization effects with controlled precision can help understand the physical mechanisms that cause depolarization.