In this paper we study the tailoring of photon spectral properties generated by four-wave mixing in a birefringent photonic crystal fibre (PCF). The aim is to produce intrinsically narrow-band photons and hence to achieve high non-classical interference visibility and generate high fidelity entanglement without any requirement for spectral filtering, leading to high effective detection efficiencies. We show unfiltered Hong-Ou-Mandel interference visibilities of 77% between photons from the same PCF, and 80% between separate sources. We compare results from modelling the PCF to these experiments and analyse photon purities.
@article{arxiv.1102.4415,
title = {Intrinsically narrowband pair photon generation in microstructured fibres},
author = {Alex Clark and Bryn Bell and Jeremie Fulconis and Matthaeus M. Halder and Ben Cemlyn and Olivier Alibart and Chunle Xiong and William J. Wadsworth and John G. Rarity},
journal= {arXiv preprint arXiv:1102.4415},
year = {2012}
}