A 6-cm Cryogenic Silicon Cavity at 4 K with Crystalline AlGaAs Coatings
POSTER
Abstract
Advancements in ultra-stable lasers locked to cryogenic resonators have enabled the rapid characterization of optical lattice clocks [1] and aided in setting new limits in tabletop investigations of fundamental physics [2]. The performance of these ultra-stable laser systems is fundamentally limited by Brownian thermal noise. For cryogenic cavities, the Brownian noise of the optical mirror coatings is the primary limitation, so characterizing coatings with low mechanical loss is an important step towards building narrower-linewidth lasers. We have developed a 6-cm single-crystal silicon cavity at 4 K with Al0.92Ga0.08As/GaAs crystalline mirror coatings [3]. We expect a fractional frequency instability of 1.3 x 10-17, a 5-fold improvement over an equivalent cavity geometry with dielectric coatings [4]. Frequency noise associated with the large birefringent mode splitting of these crystalline mirror coatings is identified [5]. We employ dual-tone probing of the two polarization eigenmodes of the cavity to cancel this birefringent noise. We present recent improvements to this ultra-stable laser system and investigations into the character of this observed birefringent noise.
[1] Oelker et al., Nat. Photonics 13, 714-719 (2019).
[2] Kennedy et al., Phys. Rev. Lett. 125 201302 (2020).
[3] Cole et al., Optica 3, 647-656 (2016).
[4] Robinson et al., Optica 6, 240-243 (2019).
[5] Yu et al., IEEE EFTF-IFCS, July 7-17 (2021).
[1] Oelker et al., Nat. Photonics 13, 714-719 (2019).
[2] Kennedy et al., Phys. Rev. Lett. 125 201302 (2020).
[3] Cole et al., Optica 3, 647-656 (2016).
[4] Robinson et al., Optica 6, 240-243 (2019).
[5] Yu et al., IEEE EFTF-IFCS, July 7-17 (2021).
*DARPA, AFOSR, NIST, EMPIR
Presenters
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Alexander Staron
- JILA, NIST, and University of Colorado, 440 UCB, Boulder, Colorado 80309, USA
- University of Colorado, Boulder