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Q: Fachverband Quantenoptik und Photonik
Q 59: Precision Measurements and Metrology II (joint session Q/A)
Q 59.7: Poster
Thursday, March 17, 2022, 16:30–18:30, P
Frequency stability of a cryogenic silicon resonator with crystalline mirror coatings — •Jialiang Yu1, Thomas Legero1, Fritz Riehle1, Daniele Nicolodi1, Sophia Herbers1, Chun Yu Ma1, Dhruv Kedar2, Eric Oelker3, Jun Ye2, and Uwe Sterr1 — 1Physikalisch-Technische Bundesanstalt (PTB), Braunschweig, Germany — 2JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado, USA — 3University of Glasgow, UK
The state-of-the-art performance of ultra-stable lasers is limited by various noise contributions like Brownian thermal noise of the optical coatings. In our 21 cm long optical resonator at 124 K, made from single-crystal silicon with low noise Al0.92Ga0.08As/GaAs crystalline mirror coatings, we have investigated a new type of noise associated with the birefringence of these coatings.
To elucidate its nature we have expanded our set-up to lock two independent laser frequencies to two polarization eigenmodes of the resonator, separated by 200 kHz. The observed anti-correlated fluctuations allowed us to cancel the birefringence noise by taking their mean, resulting in an instability below 3.5 · 10−17. We investigated spatial noise correlations by observing the fluctuations of the difference frequency between TEM00 and TEM01 modes, and find that local noise like Brownian thermal noise of the coating is below 10−17, consistent with previous estimates. However, there is significant excess noise; most likely from the coating’s semiconducting properties.