Bonn 2025 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 26: Precision Spectroscopy of Atoms and Ions V (joint session A/Q)
A 26.1: Hauptvortrag
Donnerstag, 13. März 2025, 11:00–11:30, KlHS Mathe
Breaking the barrier of resolution in broadband spectroscopy — •Jérémie Pilat1,2, Bingxin Xu1,2, Theodor W. Hänsch1,3, and Nathalie Picqué1,2 — 1Max-Planck Institute of Quantum Optics, Garching, Germany — 2Max Born Institute, Berlin, Germany — 3Ludwig-Maximilian University of Munich, Faculty of Physics, München, Germany
We provide the first experimental demonstration of a new type of spectroscopy with theoretically unlimited resolution and spans, which opens up new opportunities in broadband spectroscopy. We use a dual-comb spectrometer, where two frequency combs of narrow, equidistant lines with slightly different line spacing beat on a photodetector. Optical frequencies are mapped to measurable radiofrequencies. While dual-comb spectroscopy has existed for over a decade, we experimentally exploit here that its fundamentally different operation principle for the first time: as a pure time-domain spectrometer, it encounters no geometric limitations. As an illustration, combs of a narrow line spacing of 2.5 MHz are harnessed for sampling the 5S-SP transitions of Rubidium over a span of 130 GHz. More than 50000 comb lines are resolved in a single measurement of just one second. To achieve this resolution with a Fourier transform spectrometer, one would need a delay line of 60 m, and for a dispersive spectrometer, a grating of 60 m length.
Keywords: interferometry; dual-comb spectroscopy; optical frequency comb; heterodyne; precision spectroscopy