Publications by Steven Kolthammer

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

Optics express 26 (2018) 24678-24686

MT Posner, T Hiemstra, PL Mennea, RHS Bannerman, UB Hoff, A Eckstein, W Steven Kolthammer, IA Walmsley, DH Smith, JC Gates, PGR Smith

Direct UV-written waveguides are fabricated in silica-on-silicon with birefringence of (4.9 ± 0.2) × 10<sup>-4</sup>, 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 GeCl<sub>4</sub> and BCl<sub>3</sub> using the flame hydrolysis deposition process. The technology provides a route towards the scalability of silica-on-silicon integrated components for photonic quantum experiments.

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