CMOS-Compatible Source Design for Visible-Telecom Photon-Pairs With Simultaneous Polarization-Entanglement and Spectral-Purity

Abstract

We propose integrated photonic sources based on spontaneous four-wave mixing (SFWM) in dispersion engineered silicon nitride (SiN) nanowaveguides capable of generating spectrally-pure polarization-entangled photon-pairs bridging the visible-NIR and telecom bands. A simple silica-clad SiN waveguide design with height 640 nm and width in the range 860–960 nm can generate polarization-entangled photon pairs that simultaneously offers high heralded single photon purity of $>$99% and concurrence upto 0.99, with signal and idler lying in the range $\sim$736–740 nm and $\sim$1460–1560 nm, respectively, employing a pulsed pump (BW $\gtrsim$0.25–3 THz) of wavelength near $\sim$1-$\mu$m. Slightly different waveguide height of 620 nm and corresponding waveguide widths in the range 1040–1180 nm, offering the same purity and concurrence standards, can also address various quantum memories demonstrated at the visible-NIR wavelengths of $\sim$775–800 nm with a telecom band interface. Such CMOS-compatible on-chip sources of spectrally-pure polarization-entangled photon pairs can potentially be employed in a scalable manner for various optical quantum technologies.