State-of-the-art photon sources based on spontaneous parametric down-conversion (SPDC) currently rely on artificial structuring of the material nonlinearity to satisfy phase-matching conditions. This technique, known as periodic poling, is available only in a limited number of material platforms and introduces additional fabrication steps and errors, which are detrimental to up-scaling efforts. Here, we present a device architecture that enables SPDC of a wide range of frequencies without the need for periodic poling. We present explicit designs and calculations for 4H Silicon Carbide on-insulator, in which SPDC photon generation is so far unavailable, and thin-film Lithium Niobate on-insulator, a state-of-the-art quantum photonics platform. Our design, based on mode conversion and subsequent modal phase-matched SPDC, facilitates a CMOS compatible χ(2) platform, and simplifies photon sources by removing the requirement of periodic poling and the associated additional fabrication complexity.
@article{arxiv.2604.17723,
title = {Poling-free Spontaneous Parametric Down Conversion without for Silicon Carbide and Lithium Niobate photonics},
author = {Tim F. Weiss and Hamed Arianfard and Yang Yang and Alberto Peruzzo},
journal= {arXiv preprint arXiv:2604.17723},
year = {2026}
}