Tailoring PDC speckle structure

Speckle structure of parametric down conversion light has recently received a large attention due to relevance in view of applications to quantum imaging The possibility of tailoring the speckle size by acting on the pump properties is an interesting tool for the applications to quantum imaging and in particular to the detection of weak object under shot-noise limit. Here we present a systematic detailed experimental study of the speckle structure produced in type II PDC with particular attention to its variation with pump beam properties.