Bonn 2025 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 60: Precision Spectroscopy of Atoms and Ions VI (joint session A/Q)
Q 60.7: Vortrag
Donnerstag, 13. März 2025, 16:15–16:30, KlHS Mathe
Development of a non-collinear enhancement resonator for a VUV frequency comb nuclear clock laser — •Stephan H. Wissenberg1,2,3, Johannes Weitenberg1,4, Akira Ozawa4, Tamila Teschler2, Mahmood I. Hussain3, Peter G. Thirolf3, Hans-Dieter Hoffmann1, and Constantin L. Haefner1,2 — 1Fraunhofer ILT, Aachen — 2RWTH Aachen University, Aachen — 3LMU, Munich — 4MPQ, Garching
229-Thorium is unique in possessing a nuclear transition energy accessible by current laser technology, making it suitable for a nuclear clock's operation. To drive the nuclear transition, we are building a vacuum-ultraviolet (VUV) frequency comb at 148 nm, derived from a high-power infrared frequency comb via resonator-assisted high-harmonic generation (HHG). Our design features a non-collinear enhancement resonator where two intersecting circulating beams enable efficient geometric output-coupling of the VUV beam. Synchronizing and aligning these beams poses a challenge. We describe a resonator design employing wedge mirrors which avoids the need for separate mirrors for the two circulating beams, providing intrinsic synchronization and alignment. We provide detailed characterization measurements using a cw-laser to showcase the versatility of this non-collinear resonator design. Furthermore, cylindrical mirrors are incorporated to modify the focus's ellipticity, reducing cumulative plasma effects. Achieved ellipticities of ε > 3 do not compromise the resonator's enhancement factor of >50. Work supported by the ERC Synergy Grant 'ThoriumNuclearClock' (Grant 856415).
Keywords: non-collinear enhancement resonator; high-harmonic generation; geometrical output-coupling; frequency comb; nuclear clock