Visible-Telecom Entangled-Photon Pair Generation with Integrated Photonics: Guidelines and a Materials Comparison

Correlated photon-pair sources are key components for quantum computing, networking, synchronization, and sensing applications. Integrated photonics has enabled chip-scale sources using nonlinear processes, producing high-rate time–energy and polarization entanglement at telecom wavelengths with sub-100 microwatt pump power. Many quantum systems operate in the visible or near-infrared ranges, necessitating visible-telecom entangled-pair sources for connecting remote systems via entanglement swapping and teleportation. This study evaluates biphoton pair generation and time–energy entanglement through spontaneous four-wave mixing in various nonlinear integrated photonic materials, including silicon nitride, lithium niobate, aluminum gallium arsenide, indium gallium phosphide, and gallium nitride. We demonstrate how geometric dispersion engineering facilitates phase-matching for each platform and reveals unexpected results, such as robust designs to fabrication variations and a Type-1 cross-polarized phase-matching condition for III–V materials that expands the operational wavelength range.