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THU: Thursday Contributed Sessions

THU 13: Poster Session: Applications

THU 13.28: Poster

Thursday, September 11, 2025, 16:30–18:30, ZHG Foyer 1. OG

Mid-infrared quantum spectroscopy in a dispersion-engineered integrated SU(1,1) interferometer — •Abira Gnanavel, Franz Roeder, René Pollmann, Olga Brecht, Laura Padberg, Christof Eigner, Benjamin Brecht, and Christine Silberhorn — Paderborn University, Integrated Quantum Optics, Institute for Photonic Quantum Systems (PhoQS), Warburger Straße 100, 33098 Paderborn, Germany

Mid-infrared (MIR) spectroscopy is an important tool for sample characterization and environmental monitoring. For example, greenhouse gases exhibit distinct transition lines, which provide fingerprint-like absorption features. However, classical MIR spectroscopy is limited by costly, inadequate detectors. Nonlinear quantum interferometry with undetected photons offers a solution, where the long-wavelength photon of a photon-pair interacts with a sample under test in a nonlinear interferometer, while information is then read out by detecting only the short-wavelength photon at the output of the interferometer.
Here, we present an ultra-broadband SU(1,1) interferometer based on a dispersion-engineered integrated photon-pair source that generates bi-photons in the near-infrared (NIR) and MIR. We demonstrate quantum spectroscopy with undetected photons by measuring the transmission of UV fused silica in the MIR while only detecting the NIR photons with off-the-shelf single photon detection. This result paves the way towards miniaturized and cost effective MIR sensors for future industrial applications.