Four-photon scattering in birefringent fibers

TL;DR

This paper develops a quantum theory for four-photon scattering in birefringent fibers, analyzing spectral properties and entanglement of photon pairs generated in fibers with different birefringence levels.

Contribution

It introduces a comprehensive quantum theoretical framework for vectorial four-photon scattering in birefringent fibers, extending previous scalar models.

Findings

Spectral properties of photon pairs depend on fiber birefringence

Vectorial scattering enables polarization-entangled photon pairs

High-birefringence fibers produce distinct quantum correlations

Abstract

Four-photon scattering in nonlinear waveguides is an important physical process that allows photon-pair generation in well defined guided modes, with high rate and reasonably low noise. Most of the experiments to date used the scalar four-photon scattering process in which the pump photons and the scattered photons have the same polarization. In birefringent waveguides, vectorial four-photon scattering is also allowed: these vectorial scattering processes involve photons with different polarizations. In this article, the theory of four-photon scattering in nonlinear, birefringent, and dispersive fibers is developed in the framework of the quantum theory of light. The work focusses on the spectral properties and quantum correlations (including entanglement) of photon-pairs generated in high-birefringence and low-birefringence fibers.