Modelling and optimization of photon pair sources based on spontaneous parametric down-conversion

TL;DR

This paper presents a computationally efficient model for photon pair sources based on spontaneous parametric down-conversion, incorporating a new phase matching approximation and analyzing spectral properties for optimized quantum light generation.

Contribution

It introduces a paraxial approximation and a cosine-Gaussian phase matching model for improved simulation of photon pair sources, enabling better design of uncorrelated photon generation.

Findings

The paraxial approximation reduces computational complexity significantly.

The cosine-Gaussian model extends the parameter range for accurate phase matching.

Strategies for generating spectrally uncorrelated photons are evaluated.

Abstract

We address the problem of efficient modelling of photon pairs generated in spontaneous parametric down-conversion and coupled into single-mode fibers. It is shown that when the range of relevant transverse wave vectors is restricted by the pump and fiber modes, the computational complexity can be reduced substantially with the help of the paraxial approximation, while retaining the full spectral characteristics of the source. This approach can serve as a basis for efficient numerical calculations, or can be combined with analytically tractable approximations of the phase matching function. We introduce here a cosine-gaussian approximation of the phase matching function which works for a broader range of parameters than the gaussian model used previously. The developed modelling tools are used to evaluate characteristics of the photon pair sources such as the pair production rate and the spectral purity quantifying frequency correlations. Strategies to generate spectrally uncorrelated photons, necessary in multiphoton interference experiments, are analyzed with respect to trade-offs between parameters of the source.