Regensburg 2025 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 8: Measurement Technology and Cryogenics
TT 8.5: Talk
Monday, March 17, 2025, 16:00–16:15, H32
Electro-optic cavities: Towards local measurement of light-matter coupling — •Michael S. Spencer1, Joanna M. Urban1, Maximilian Frenzel1, Niclas S. Mueller1, Olga Minakova1, Martin Wolf1, Alexander Paarmann1, and Sebastian F. Maehrlein1,2,3 — 1FHI Berlin — 2HZDR — 3TU Dresden
Cavity quantum electrodynamics is expected to provide a unique direction for tailoring ground- and excited-state properties in correlated materials. Bringing this together with high-field driving in the terahertz (THz) spectral range opens the door to explore low-energy, field-driven cavity electrodynamics. Despite this potential, leveraging field-driven material control in bulk cavities is hindered by the lack of direct retrieval of intra-cavity fields. Here, we demonstrate novel active cavities, consisting of a Fabry-Pérot cavity filled with an electro-optic crystal, which measure their intra-cavity electric fields on ultrafast timescales. With these, we demonstrate quantitative retrieval of the cavity modes in amplitude and phase. We furthermore design a tunable multi-layer cavity, enabling deterministic design of hybrid cavities for future field-resolved polaritonic systems. Our theoretical modeling reveals the origin of the avoided crossings embedded in the intricate mode dispersion upon cavity tuning and enable fully-switchable polaritonic effects within arbitrary materials hosted by the hybrid cavity. Electro-optic cavities will therefore serve as in-situ probes of light-matter interactions across all coupling regimes, laying the foundation for field-resolved intra-cavity quantum electrodynamics.
Keywords: Cavity Physics; Terahertz; Polaritons; Polaritonics; Electro-Optic Effect