Abstract

A photon-pair in 1550nm band is an essential resource for the practical quantum communication systems such as quantum key distribution and quantum teleportation. The photon-pairs can be easily generated by the spontaneous parametric down conversion (SPDC) in a second-order nonlinear crystal. Using a periodically poled lithium niobate (PPLN) waveguide, we can generate photon-pairs in 1550nm band efficiently, which is due to the long interaction length and the strong confinement of the pumping energy. The PPLN waveguide has utilized the nonlinear tensor element d₃₃ for the Type-0 quasi-phase matching (QPM) in which the copolarized photon-pairs were generated. Since the element d₃₃ has the higher nonlinear coefficient than any other elements, Type-0 PPLN waveguide has the highest conversion efficiency. Therefore, the Type-0 PPLN waveguide can be available for the efficient single-photon emitter and sharing the entangled photons between distant parties. However, since the SPDC bandwidth of the Type-0 PPLN waveguide is generally very broad (~THz), the Type-0 PPLN waveguide is not appropriate for the advanced systems such as a long-distance quantum teleportation system in which a narrowband photon-pair source is essential.

© 2007 IEEE