Parameter optimization for observation of high-dimensional effect in orbital angular momentum entanglement

Anharmonic behavior of coincidence count rate obtained with the hologram shifting method can be used to probe highdimensional effect of orbital angular momentum entangled photon pairs. We perform numerical analysis for the case where the photon pairs are created by spontaneous parametric downconversion, and both photons are observed through singlemode fibers after mode conversion with phase-only holograms. The center of the holograms are shifted by a constant distance from the beam axis and the relative shift direction is scanned. We explore effects of pump beam width and crystal length with respect to the hologram shift distance.