Efficient generation of polarization-entangled photons in a nonlinear crystal
- Cite this article as:
- Wong, F.N.C., Shapiro, J.H. & Kim, T. Laser Phys. (2006) 16: 1517. doi:10.1134/S1054660X06110053
We review the use of bidirectional pumping and collinear propagation in type-II phase-matched periodically poled KTiOPO4 to achieve efficient generation of polarization-entangled photons via spontaneous parametric downconversion. The advantages of this approach are fully exploited in our optimized polarization Sagnac interferometric source. Its measured flux of 4700 polarization-entangled photon pairs/s per milliwatt of pump power in a 1-nm bandwidth exhibited 99% quantum-interference visibility. We also present a plane-wave Gaussian state theory for continuous-wave spontaneous parametric downconversion. This formulation affords the complete description of multiple-pair emissions that is needed for quantum communication analyses while reducing to the usual biphoton-state description at low generation rates.