The transverse correlation between the pairs of photons produced in optical spontaneous parametric down-conversion is analyzed. The interesting features of the correlation arise from the form of the two-photon state generated in the process. The physics of the rings of radiation emerging from the crystal is described. We discuss the theory behind the recent experiments on two-photon geometric and physical optics. © 1996 The American Physical Society.

• Received 12 August 1996

DOI:https://doi.org/10.1103/PhysRevA.54.5349