Open AccessNonlinear amplification of side-modes in frequency combs
Author(s) -
Rafael A. Probst,
Tilo Steinmetz,
Tobias Wilken,
H. Hundertmark,
Sebastian Stark,
G. K. L. Wong,
P. St. J. Russell,
Theodor W. Hänsch,
Ronald Holzwarth,
Th. Udem
Publication year - 2013
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.21.011670
Subject(s) - optics , physics , modulation (music) , phase modulation , frequency modulation , calibration , phase (matter) , nonlinear optics , spectrograph , self phase modulation , nonlinear system , frequency comb , fabry–pérot interferometer , doppler broadening , wavelength , spectral line , phase noise , bandwidth (computing) , telecommunications , laser , acoustics , quantum mechanics , astronomy , computer science
We investigate how suppressed modes in frequency combs are modified upon frequency doubling and self-phase modulation. We find, both experimentally and by using a simplified model, that these side-modes are amplified relative to the principal comb modes. Whereas frequency doubling increases their relative strength by 6 dB, the growth due to self-phase modulation can be much stronger and generally increases with nonlinear propagation length. Upper limits for this effect are derived in this work. This behavior has implications for high-precision calibration of spectrographs with frequency combs used for example in astronomy. For this application, Fabry-Pérot filter cavities are used to increase the mode spacing to exceed the resolution of the spectrograph. Frequency conversion and/or spectral broadening after non-perfect filtering reamplify the suppressed modes, which can lead to calibration errors.