We present experimental realization of type-II spontaneous parametric down-conversion in a periodically poled potassium titanyl phosphate (KTiOPO4) nonlinear waveguide. We demonstrate that by careful exploitation of intermodal dispersion in the waveguide it is feasible to produce photon pairs in well defined transverse modes without any additional spatial filtering at the output. Spatial characteristics is verified by measurements of the M2 beam quality factors. We also prepared a postselected polarization-entangled two-photon state shown to violate Bell's inequality. Similar techniques based on intermodal dispersion can be used to generate spatial entanglement and hyperentanglement.
Cite
@article{arxiv.1209.5349,
title = {Generation of spatially pure photon pairs in a multimode nonlinear waveguide using intermodal dispersion},
author = {Michal Karpinski and Czeslaw Radzewicz and Konrad Banaszek},
journal= {arXiv preprint arXiv:1209.5349},
year = {2012}
}
Comments
11 pages, 5 figures, submitted to Proceedings of Quantum Communications and Quantum Imaging X Conference at SPIE 2012 Optics + Photonics, San Diego, 12-16 August 2012