We report on the generation of photon pairs in the 1550-nm band suitable for long-distance fiber-optic quantum key distribution. The photon pairs were generated in a periodically poled lithium niobate waveguide with a high conversion-efficiency. Using a pulsed semiconductor laser with a pulse rate of 800 kHz and a maximum average pump power of 50 muW, we obtained a coincidence rate of 600 s^-1. Our measurements are in agreement with a Poissonian photon-pair distribution, as is expected from a comparison of the coherence time of the pump and of the detected photons. An average of 0.9 photon pairs per pulse was obtained.
@article{arxiv.quant-ph/0509186,
title = {On the distribution of 1550-nm photon pairs efficiently generated using a periodically poled lithium niobate waveguide},
author = {Shigehiko Mori and Jonas Soderholm and Naoto Namekata and Shuichiro Inoue},
journal= {arXiv preprint arXiv:quant-ph/0509186},
year = {2007}
}