In this paper we present a compact source of narrow-band energy-time entangled photon pairs in the telecom regime based on a Ti-indiffused Periodically Poled Lithium Niobate (PPLN) waveguide resonator, i.e. a waveguide with end-face dielectric multi-layer mirrors. This is a monolithic doubly resonant Optical Parametric Oscillator (OPO) far below threshold, which generates photon pairs by Spontaneous Parametric Down Conversion (SPDC) at around 1560nm with a 117MHz (0.91 pm)- bandwidth. A coherence time of 2.7 ns is estimated by a time correlation measurement and a high quality of the entangled states is confirmed by a Bell-type experiment. Since highly coherent energy-time entangled photon pairs in the telecom regime are suitable for long distance transmission and manipulation, this source is well suited to the requirements of quantum communication.
@article{arxiv.0909.1208,
title = {Waveguide-based OPO source of entangled photon pairs},
author = {Enrico Pomarico and Bruno Sanguinetti and Nicolas Gisin and Robert Thew and Hugo Zbinden and Gerhard Schreiber and Abu Thomas and Wolfgang Sohler},
journal= {arXiv preprint arXiv:0909.1208},
year = {2013}
}