Highly efficient generation of pulsed photon pair using a bulk Periodically Poled Potassium Titanyl Phosphate

In this paper, we demonstrate efficient generation of collinearly propagating, degenerate pulsed photon pairs based on a bulk Periodically Poled Potassium Titanyl Phosphate pumped by an ultrashort pulse laser. Using a single-mode fiber as a spatial mode filter, we detect about 3200 coincidence counts per second per milliwatt pump power. After we consider main losses in our experiment, the inferred coincidence counts are about 109000 per second per milliwatt pump power. This is the very promising for realization of sources for quantum communication and metrology.