Highly efficient generation of pulsed photon pairs with bulk periodically poled potassium titanyl phosphate

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 approximately 3200 coincidence counts per second per milliwatt pump power in a Hanbury–Brown–Twiss-type experiment. The estimated photon-pair production rate is approximately 1.05 MHz/mW pump power. This is very promising for the realization of sources for quantum communication and metrology.