title: Silicon single-crystal cryogenic optical resonator.
abstract: We report on the demonstration and characterization of a silicon optical resonator for laser frequency stabilization, operating in the deep cryogenic regime at temperatures as low as 1.5 K. Robust operation was achieved, with absolute frequency drift less than 20 Hz over 1 h. This stability allowed sensitive measurements of the resonator thermal expansion coefficient (α). We found that α=4.6×10(-13)  K(-1) at 1.6 K. At 16.8 K α vanishes, with a derivative equal to -6×10(-10)  K(-2). The temperature of the resonator was stabilized to a level below 10 μK for averaging times longer than 20 s. The sensitivity of the resonator frequency to a variation of the laser power was also studied. The corresponding sensitivities and the expected Brownian noise indicate that this system should enable frequency stabilization of lasers at the low-10(-17) level.
authors.forename: Eugen
authors.initials: E
authors.lastname: Wiens
authors.forename: Qun-Feng
authors.initials: QF
authors.lastname: Chen
authors.forename: Ingo
authors.initials: I
authors.lastname: Ernsting
authors.forename: Heiko
authors.initials: H
authors.lastname: Luckmann
authors.forename: Ulrich
authors.initials: U
authors.lastname: Rosowski
authors.forename: Alexander
authors.initials: A
authors.lastname: Nevsky
authors.forename: Stephan
authors.initials: S
authors.lastname: Schiller