Ultra-stable transportable ultraviolet clock laser using cancellation between photo-thermal and photo-birefringence noise

authored by
Benjamin Kraus, Sofia Herbers, Constantin Nauk, Uwe Sterr, Christian Lisdat, Piet o. Schmidt
Abstract

Optical clocks require an ultra-stable laser to probe and precisely measure the frequency of the narrow-linewidth clock transition. We introduce a portable ultraviolet (UV) laser system for use in an aluminum quantum logic clock, demonstrating a fractional frequency instability of approximately mod σy = 2 × 10-16. The system is based on an ultra-stable cavity with crystalline AlGaAs/GaAs mirror coatings, with a frequency quadrupling system employing two single-pass second-harmonic generation (SHG) stages. Its acceleration sensitivity, measured in all three axes, does not exceed 4(2) × 10-12/(ms-2) and is among the lowest recorded for transportable systems to date. Additionally, partial cancellation between photo-thermal noise and photo-birefringence noise is used to effectively mitigate noise induced by intra-cavity optical power fluctuation at lower Fourier frequencies.

Organisation(s)
Institute of Quantum Optics
External Organisation(s)
Physikalisch-Technische Bundesanstalt PTB
Type
Article
Journal
Optics letters
Volume
50
Pages
658-661
No. of pages
4
ISSN
0146-9592
Publication date
14.01.2025
Publication status
Published
Peer reviewed
Yes
ASJC Scopus subject areas
Atomic and Molecular Physics, and Optics
Electronic version(s)
https://doi.org/10.1364/OL.544907 (Access: Open)