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### Photon-Pair Generation in Chalcogenide Glass: Role of Waveguide Linear Absorption

Photon-Pair Generation in Chalcogenide Glass: Role of Waveguide Linear Absorption, Proc INSTICC International Conf. on Photonics, Optics and Laser Technology - PHOTOPTICS, Lisboa, Portugal, Vol. 1, pp. 5 - 10, January, 2014.

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Abstract
We investigate the impact of waveguide loss on the generation rate of quantum correlated photon-pairs through four-wave mixing in a chalcogenide glass fiber. The obtained results are valid even when the photon-pairs are generated in a medium with non-negligible loss, $\alpha L\gg 1$. The impact of the loss is quantified through the analysis of the true, total and accidental counting rates at waveguide output. We use the coincidence-to-accidental ratio (CAR) as a figure of merit of the photon-pair source. Results indicate that, the CAR parameter tends to decrease with the increase of the waveguide length, until $L<1/\alpha$. However, a continuous increase of the waveguide length tends to lead to an increase on the CAR value. In that non-negligible loss regime, $\alpha L\gg 1$, we are able to observe a significant decrease on the value of all coincidence counting rates. Nevertheless, that decrease is even more pronounced on the accidental counting rate. Moreover, for waveguide length $L= 10/\alpha$ we are able to obtain a CAR of the order of 70, which is higher than the CAR value for the specific case of $\alpha=0$ with $L=2$~cm, i.e. CAR=42. This indicates that the waveguide loss can improve the degree of quantum correlation between the photon-pairs.