Paper detail

Tailoring the down conversion emission profile via direct imaging with a camera

We present the analysis of emission profile of downconverted photons from a critically phase-matched nonlinear crystal. This is done via direct imaging of down converted photons by a CMOS camera. The effects of nonlinear crystal thickness in collinear and non-collinear geometries on the down converted photon pair rate is directly observed and the experimental results show that the photon pair rate increases linearly with the crystal thickness. However, the rate of the photon pairs collected to a single mode fiber goes quadratically with the crystal length because of the cylindrical asymmetries in the optical path and the exit angle around the pump mode within the nonlinear crystal. The use of cameras for real-time and direct imaging of down conversion emission profile significantly simplifies the phase-matching alignments and the collecting the entangled photons.