Polarization entanglement generation at 1.5 um based on walk-off effect due to fiber birefringence

TL;DR

This paper presents a linear fiber-based method to generate polarization-entangled photon pairs at 1.5 μm using birefringence effects in PM-DSF, achieving high interference visibility suitable for quantum communication.

Contribution

It introduces a novel scheme utilizing birefringent walk-off and polarization axis offset in PM-DSF to produce stable polarization entanglement at telecom wavelengths.

Findings

Achieved 89% two-photon interference fringe visibility.

Demonstrated indistinguishability and entanglement in fiber-based setup.

Potential for stable, efficient quantum light sources in optical communications.

Abstract

In this Letter, a linear scheme to generate polarization entanglement at 1.5 um based on commercial polarization maintained dispersion shifted fiber (PM-DSF) is proposed. The birefringent walk-off effect of the pulsed pump light in the PM-DSF provides an effective way to suppress the vector scattering processes of spontaneous four wave mixing. A 90 degree offset of fiber polarization axes is introduced at the midpoint of the fiber to realize the quantum superposition of the two correlated photon states generated by the two scalar processes on different fiber polarization axes, leading to polarization entanglement generation. Experiments of the indistinguishable property on single side and two-photon interference in two non-orthogonal polarization bases are demonstrated. A two photon interference fringe visibility of 89\pm3% is achieved without subtracting the background counts, demonstrating its great potential in developing highly efficient and stable fiber based polarization-entangled quantum light source at optical communication band.