Waveguide-based OPO source of entangled photon pairs

TL;DR

This paper introduces a compact, waveguide-based OPO source of narrow-band, energy-time entangled photon pairs at telecom wavelengths, suitable for long-distance quantum communication, with high coherence and confirmed entanglement quality.

Contribution

It presents a monolithic doubly resonant PPLN waveguide OPO producing high-quality entangled photon pairs at 1560nm with narrow bandwidth and long coherence time.

Findings

Photon pairs generated at 1560nm with 117MHz bandwidth

Coherence time of 2.7 ns confirmed by measurements

High entanglement quality verified by Bell test

Abstract

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.