A high-flux entanglement source based on a doubly resonant optical parametric amplifier
Christopher E. Kuklewicz, Eser Keskiner, Franco N. C. Wong, Jeffrey H. Shapiro · Journal of Optics B Quantum and Semiclassical Optics · 2002
A 532 nm pumped type-II phase-matched, doubly resonant KTP optical parametric amplifier (OPA) was operated near frequency degeneracy to yield an inferred downconverted photon pair production rate of 1.7×10 6 s -1 at a pump power of 100 µW. The OPA output consisted of three components: narrowband doubly resonant mode pairs; narrowband singly resonant mode pairs for which either the signal or idler was resonant with the cavity and broadband nonresonant mode pairs. Under frequency-degenerate operation, the broadband nonresonant mode pairs were polarization triplet states. We observed quantum interference between the orthogonally polarized photons of the triplet states when they were analysed with a polarizer set at 45° relative to the OPA's output polarizations, leading to reduced coincidence counts.