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xtal stable Performance Confirmed

Mechanical ringdown studies of large-area substrate-transferred GaAs/AlGaAs crystalline coatings

Together with our collaborators from American University and Hobart and William Smith Colleges, we are proud to announce the latest confirmation of the low elastic loss of our xtal stable™ Semiconductor Supermirrors. Direct mechanical ringdown measurements performed on ~70-mm diameter coatings transferred to fused silica showed that such coatings on equivalent reference cavity end mirrors would exhibit 10× lower losses than traditional sputtered mirrors. These results have been published in the Journal of the Optical Society of America B (JOSA B) in a Feature Issue on Fluctuation-Induced Phenomena in Photonic Systems. Please find the published results here, or click to the pre-print.

Full reference:

S. D. Penn, M. M. Kinley-Hanlon, I. A. O. MacMillan, P. Heu, D. Follman, C. Deutsch, G. D. Cole, and G. M. Harry, “Mechanical ringdown studies of large-area substrate-transferred GaAs/AlGaAs crystalline coatings,” Journal of the Optical Society of America B (JOSA B), vol. 36, no. 4, C15-C21, 1 April 2019


“We investigated elastic loss in GaAs/AlGaAs multilayers to help determine the suitability of these coatings for future gravitational wave detectors. We measured large (70-mm diameter) substrate-transferred crystalline coating samples with an improved substrate polish and bonding method. The elastic loss, when decomposed into bulk and shear contributions, was shown to arise entirely from the bulk loss, 𝜙bulk=(5.33±0.03)×10^4, with 𝜙shear=0.0+5.20.0×10^7. These results predict the coating loss of an 8-mm diameter coating in a 35-mm long cavity with a 250-μm spot size (radius) to be 𝜙coating=(4.78±0.05)×10^5, in agreement with the published result from direct thermal noise measurement of 𝜙coating=(4±4)×10^5. Bonding defects were shown to have little impact on the overall elastic loss.”