Mainz 2026 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 10: Quantum Technologies – Photon Detectors and Sources

Q 10.2: Talk

Monday, March 2, 2026, 17:15–17:30, P 5

Spectro-Temporal Study of Photon Pairs from a Lithium Niobate Waveguide Resonator — •Stefan Kazmaier and Kaisa Laiho — Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Quantentechnologien, Wilhelm-Runge-Straße 10, 89081 Ulm

Lithium niobate is one of the most widely used platforms for generating photon pairs, usually called signal and idler, via parametric down-conversion (PDC). Here we characterize a commercially available type-II periodically-poled lithium niobate waveguide (PPLN-WG) with highly reflecting end-facets forming a resonator at the PDC wavelengths. We measure conventional key figures of merit of our PDC source, including the coincidence-to-accidentals ratio (CAR), Klyshko efficiencies, and the temporal profile of signal and idler. Furthermore, by independently measuring the optical path length difference of signal and idler, we additionally extract the phasematching bandwidth, the group delay, and the resonators cluster spacing [1]. These results provide a comprehensive performance assessment of the device and support its use in quantum optics and integrated photonics applications.

[1] Kazmaier and Laiho, Phys. Scr. 100, 081502 (2025).

Keywords: Lithium Niobate Waveguide; Photon Pair characterization; Optical Resonator; Parametric down-conversion