High-birefringence direct UV-written waveguides for heralded single-photon sources at telecommunication wavelengths

TL;DR

This paper reports the development of high-birefringence UV-written silica waveguides suitable for generating heralded single photons at telecom wavelengths, advancing integrated quantum photonics.

Contribution

It introduces waveguides with significantly increased birefringence in silica-on-silicon, enabling efficient photon pair generation for quantum applications.

Findings

Birefringence of (4.9 ± 0.2) × 10^{-4} achieved

Waveguide-to-fiber coupling efficiencies of 78-91%

Successful generation of spectrally uncorrelated photon pairs near 1550 nm and 800 nm

Abstract

Direct UV-written waveguides are fabricated in silica-on-silicon with birefringence of $(4.9 \pm 0.2) \times 10^{-4}$, much greater than previously reported in this platform. We show that these waveguides are suitable for the generation of heralded single photons at telecommunication wavelengths by spontaneous four-wave mixing. A pulsed pump field at 1060 nm generates pairs of photons in highly detuned, spectrally uncorrelated modes near 1550 nm and 800 nm. Waveguide-to-fiber coupling efficiencies of 78-91% are achieved for all fields. Waveguide birefringence is controlled through dopant concentration of $\mathrm{GeCl_4}$ and $\mathrm{BCl_3}$ using the flame hydrolysis deposition process. The technology provides a route towards the scalability of silica-on-silicon integrated components for photonic quantum experiments.