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Q: Fachverband Quantenoptik und Photonik
Q 29: Optomechanics I
Q 29.6: Talk
Wednesday, March 16, 2022, 12:00–12:15, Q-H13
Efficient optomechanical mode-shape mapping of micromechanical devices — David Hoch1,2,3, Timo Sommer1,2, Kevin-Jeremy Haas1, Leopold Moller1, Julius Röwe1, and •Menno Poot1,2,3 — 1Department of Physics, Technical University of Munich, Garching, Germany — 2Munich Center for Quantum Science and Technology (MCQST), Munich, Germany — 3Institute for Advanced Study, Technical of University Munich, Garching, Germany
The rapidly growing interest in (quantum) optomechanics calls for an efficient method to map eigenmode shapes. One - very time-consuming - way to do this is to measure the driven response for every mode at different locations on the resonator. A faster approach is to drive each mode at a single frequency and record their amplitudes, but drift of the resonance frequency makes this impractical for high-Q resonators. Here, we present an efficient way of simultaneously mapping up to 6 eigenmodes. Our method is robust against drift by employing an improved phase-lock loop (PLL) that can also lock to regions with different signs of the mode shape. We demonstrate the capabilities of our technique on a square Si3N4 membrane in vacuum. The membrane is excited with a piezoelectric element and modes between 1 and 21.6 MHz are mapped accurately. Proof-of-principle measurements already shine new light on e.g. mode splitting, clamping losses, and superposition of degenerate modes. Currently ongoing experiments on crosstalk compensation and on non-flat resonators are also discussed.