Modulating the spatial coherence-polarization from intensity basis addition of speckle patterns with polarization diversity

Abstract

A technique based on an intensity basis addition of two speckle patterns with polarization diversity, which are filtered from a depolarized field, is developed to modulate the spatial coherence-polarization (CP) property of the superposed speckle pattern. It is proposed theoretically, and validated both experimentally and numerically that by tuning the polarization diversity of the constituent speckle patterns, a complete control over the spatial coherence of the superposed speckle pattern can be achieved, and the superposed speckles can be modulated from fully spatially coherent to spatially incoherent in a controlled fashion. It is also observed that if the original field is not completely depolarized, the achieved modulation of the spatial coherence not only depends on the mutual orientation of the polarization vectors of the constituent speckle patterns (as in the case of the field basis addition of speckles) but also on the sum of the polarization orientations. However, the achieved modulation is found to be similar to the case of the addition of speckle patterns in the field basis, if the original field is completely depolarized. This work may have potential application in biomedical imaging, where the intensity basis addition of speckle patterns is widely used to reduce the speckle noise.