Photon-pair generation in photonic crystal fibrebre with a 1.5GHz   modelocked VECSEL
  Four-wave mixing (FWM) in optical fibre is a leading technique for generating high-quality photon pairs. We report the generation of photon pairs by spontaneous FWM in photonic crystal fibre pumped by a 1.5 GHz repetition-rate vertical-external-cavity surface-emitting laser (VECSEL). The photon pairs exhibit high count rates and a coincidence-to-accidental ratio of over 80. The VECSEL's high repetition-rate, high average power, tunability, and small footprint make this an attractive source for quantum key distribution and photonic quantum-state engineering. 
Oliver J. Morris, Robert J.A. Francis-Jones, Keith G. Wilcox, Anne C.   Tropper and Peter J. Mosley
quant-ph physics.optics