Open AccessPhase noise of frequency doublers in optical clock lasers
Author(s) -
Sofia Herbers,
Sören Dörscher,
Erik Benkler,
Christian Lisdat
Publication year - 2019
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.27.023262
Subject(s) - optics , frequency multiplier , phase noise , laser , lithium niobate , waveguide , noise (video) , materials science , phase (matter) , optoelectronics , physics , computer science , cmos , quantum mechanics , artificial intelligence , image (mathematics)
Frequency doublers are widely used in high-resolution spectroscopy to shift the operation wavelength of a laser to a more easily accessible or otherwise preferable spectral region. We investigate the use of a periodically-poled lithium niobate (PPLN) waveguide frequency doubler in an optical clock. We focus on the phase evolution between the fundamental (1396 nm) and frequency-doubled (698 nm) light and its effect on clock performance. We find that the excess phase noise of the doubler under steady-state operation is at least two orders of magnitude lower than the noise of today's best interrogation lasers. Phase chirps related to changes of the optical power in the doubler unit and their influence on the accuracy of optical clocks are evaluated. We also observe substantial additional noise when characterizing the doubler unit with an optical frequency comb instead of using two identical waveguide doublers.