Mainz 2026 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 40: Poster – Photonics
Q 40.1: Poster
Wednesday, March 4, 2026, 17:00–19:00, Philo 1. OG
Photonic integrated top-hat beam profiler for multi-ion clock application — •Matthias Ludwig1,2, Carl-Frederik Grimpe1, Guochun Du1, Fatemeh Salahshoori1, André Kulosa1, Elena Jordan1, and Tanja E. Mehlstäubler1,3,4 — 1Physikalisch-Technische Bundesanstalt, Braunschweig, Germany — 2Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany — 3Leibniz Universität Hannover, Institut für Quantenoptik, Hannover, Germany — 4Leibniz Universität Hannover, Laboratorium für Nano- und Quantenengineering, Hannover Germany
Multi-ion optical clocks offer improved precision by reducing the averaging time. To minimise intensity-dependent AC Stark shifts on individual ions, highly homogeneous illumination is essential. The optimal beam shape for this purpose is a top-hat intensity profile. This has previously been achieved using holographic waveplates in free space, but this approach limits spatial uniformity [1]. We demonstrate that an extreme mode converter, implemented on an Al2O3 photonic material platform, can generate this top-hat profile for the 370 nm Doppler cooling transition of Yb+ ions, thereby increasing the modal area of the waveguide mode by a factor of ∼ 104. This integrated photonic approach provides a path towards improved beam homogeneity and scalable multi-ion clocks, overcoming the limitations imposed by free-space optics.
[1] J. Yu et al., "Precision Spectroscopy in Yb+ ions," 2024 European Frequency and Time Forum (EFTF), Neuchâtel, Switzerland, 2024, pp. 334-336, doi: 10.1109/EFTF61992.2024.10722611.
Keywords: Nanophotonic; Extrem mode converter; Beam shaping; Ion clock; Doppler Cooling