of 2
advances.sciencemag.org/cgi/content/full/6/9/eaax6230/DC1
Supplementary Materials for
Direct Kerr frequency comb atomic spectroscopy and stabilizatio
n
Liron Stern*, Jordan R. Stone, Songbai Kang, Daniel C. Cole, My
oung-Gyun Suh, Connor Fredrick, Zachary Newman,
Kerry Vahala, John Kitching, Scott A. Diddams, Scott B. Papp*
*Corresponding author. Email: li
ron.stern@mail.huji.ac.il (L.S.
); scott.papp@nist.gov (S.B.P)
Published 28 February 2020,
Sci. Adv.
6
, eaax6230 (2020)
DOI: 10.1126/sciadv.aax6230
This PDF file includes:
Fig. S1. Kerr comb DFCS elaborate apparatus.
Fig. S1. Kerr comb DFCS elaborate apparatus.
A
n ECDL drives a single
-
sideband,
suppressed
-
carrier (SSB
-
SC) frequency shifter, driven by a voltage
-
controlled oscillator (VCO).
The pump beam is phase modulated (PM1) at
by a
synthesizer
reference
to a Hydrogen maser,
with a frequency
f
which roughly coincides with FSR of the resonator. This signal is
optically
amplified,
and its
intensity
is controlled by variable optical attenuator (VOA).
We implement a
PDH servo
-
loop to control the resonator det
uning
with a counter propagating
acoustic
-
optical
-
modulation (
AOM
)
shifted and
phased modulated (PM2) beam.
The counterpropagating signal is
circulated, detected and
demodulated
and controls a proportional intergrade derivative (PID)
controller that feeds the VCO to offset lock the pump laser.
A portion of the comb spectrum is
amplified and sent to a micromachined atomic cell, which is also illuminated by a counter
propagating CW
780 nm probe laser.
The 780 nm probe is locked to the
85
Rb
Doppler free
cycling transitions by means of a saturation spectroscopy setup.
By use of a dichroic mirror and
a Si photodetector, the 780 nm light is monitored.
Dithering the VOA at the frequency
푑푖푡
푒푟
and demodulating using
Lock
-
in amplification
(LIA) yields an error signal which is fed to
a PID
servo
to
lock
푐푒표
to the atomic transition.