Freiburg 2024 – scientific programme

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MO: Fachverband Molekülphysik

MO 25: Novel Experimental Approaches

MO 25.6: Talk

Friday, March 15, 2024, 12:15–12:30, HS 3044

Nanophotonics for precise mid-infrared molecular spectroscopy — •Jérémie Pilat¹, Lucas Deniel¹, Melissa A. Guidry², Daniil M. Lukin², Bingxin Xu¹, Kiyoul Yang², Joshua Yang², Jelena Vučković², Theodor W. Hänsch^1,3, and Nathalie Picqué^1,4 — ¹Max-Planck Institute of Quantum Optics, Garching, Germany — ²E. L. Ginzton Laboratory, Stanford University, Stanford, California, USA — ³Ludwig-Maximilian University of Munich, Faculty of Physics, München, Germany — ⁴Max Born Institute, Berlin, Germany

A nanophotonic silicon-carbide waveguide on a 5x5 mm² chip dramatically simplifies comb-assisted mid-infrared spectroscopy. The emerging 4H silicon carbide (SiC) on insulator platform provides a high refractive index, strong second- and third-order optical nonlinearity, low losses, and a broad transparency range. Here, a mode-locked laser at 1560 nm excites a dispersion-engineered SiC waveguide. This simultaneously enables frequency-comb self-referencing with an integrated f-2f interferometer and mid-infrared dispersive-wave frequency-comb generation at low 120-pJ pulse energies. By stabilizing the carrier-envelope offset frequency beatnote f_ceo provided by the integrated f-2f interferometer and the repetition rate of the mode-locked laser, accurate tunable-laser molecular spectroscopy of methane is demonstrated at 3.6 µm. Our new tool opens up new opportunities for precision measurements in the mid-infrared molecular fingerprint region, where most molecules exhibit characteristic intense rovibrational transitions, of interest to fundamental research and environmental sensing.

Keywords: frequency comb; integrated optics; frequency measurement; supercontinuum generation; chip-scale frequency comb