The effect of pump focusing on the performance of ghost imaging with entangled resource

摘要

The effect of pump focusing on the performance of ghost imaging is studied experimentally on an entangled source. Theoretical results show that the correlation properties of the entangled photon source are destroyed when the conversion crystal is pumped by a focused laser beam. The experiment is performed on a compact entangled source produced by type-II non-collinear degenerate SPDC, and the results demonstrate that the "walk off" effects almost have no effect on the image, while the pump focusing greatly degrades the visibility of the image. However, a sharp image could be reproduced in the configuration first proposed in Ref. [8] for the case with pump focusing.