29 research outputs found
Second harmonic generation at 399 nm resonant on the transition of ytterbium using a periodically poled LiNbO waveguide
We demonstrate a compact and robust method for generating a 399-nm light
resonant on the transition in ytterbium using a
single-pass periodically poled LiNbO waveguide for second harmonic
generation (SHG). The obtained output power at 399 nm was 25 mW when a 798-nm
fundamental power of 380 mW was coupled to the waveguide. We observed no
degradation of the SHG power for 13 hours with a low power of 6 mW. The
obtained SHG light has been used as a seed light for injection locking, which
provides sufficient power for laser cooling ytterbium
A frequency-stabilized light source at 399 nm using an Yb hollow-cathode lamp
We demonstrate a diode laser system operating at 399 nm that is stabilized to
the electric dipole transition in
ytterbium (Yb) atoms in a hollow-cathode lamp. The frequency stability of the
laser reached at an averaging time of $\tau = 1\
\mathrm{s}{\rm {^1}S_{0} - {^1}P_{1}}^{174}\mathrm{Yb}$ was 751 526 522.26(9) MHz. We also investigated several
systematic frequency shifts while changing some of the light source parameters
and measured several isotope shifts. The measured laser frequency will provide
useful information regarding the practical use of the frequency-stabilized
light source at 399 nm.Comment: 14 pages, 6 figures, 1 tabl
Spectroscopy and frequency measurement of the Sr clock transition by laser linewidth transfer using an optical frequency comb
We perform spectroscopic observations of the 698-nm clock transition in
Sr confined in an optical lattice using a laser linewidth transfer
technique. A narrow-linewidth laser interrogating the clock transition is
prepared by transferring the linewidth of a master laser (1064 nm) to that of a
slave laser (698 nm) with a high-speed controllable fiber-based frequency comb.
The Fourier-limited spectrum is observed for an 80-ms interrogating pulse. We
determine that the absolute frequency of the 5s S - 5s5p
P clock transition in Sr is 429 228 004 229 872.0 (1.6) Hz
referenced to the SI second.Comment: 5 pages, 4 figure
Uncertainty evaluation of an Yb optical lattice clock at NMIJ
We report an uncertainty evaluation of an Yb optical lattice clock
with a total fractional uncertainty of , which is mainly
limited by the lattice-induced light shift and the blackbody radiation shift.
Our evaluation of the lattice-induced light shift, the density shift, and the
second-order Zeeman shift is based on an interleaved measurement where we
measure the frequency shift using the alternating stabilization of a clock
laser to the \mathrm{6s^{2}\,^{1}S_{0}-6s6p\,^{3}P_{0}} clock transition with
two different experimental parameters. In the present evaluation, the
uncertainties of two sensitivity coefficients for the lattice-induced
hyperpolarizability shift incorporated in a widely-used light shift model
by RIKEN and the second-order Zeeman shift are improved
compared with the uncertainties of previous coefficients. The
hyperpolarizability coefficient is determined by investigating the trap
potential depth and the light shifts at the lattice frequencies near the
two-photon transitions ,
, and . The obtained values are
Hz and Hz/mT. These
improved coefficients should reduce the total systematic uncertainties of Yb
lattice clocks at other institutes
A compact iodine-laser operating at 531 nm with stability at the 10 level and using a coin-sized laser module
We demonstrate a compact iodine-stabilized laser operating at 531 nm using a
coin-sized light source consisting of a 1062-nm distributed-feedback diode
laser and a frequency-doubling element. A hyperfine transition of molecular
iodine is observed using the light source with saturated absorption
spectroscopy. The light source is frequency stabilized to the observed iodine
transition and achieves frequency stability at the 10 level. The
absolute frequency of the compact laser stabilized to the hyperfine
component of the transition is determined as
kHz with a relative uncertainty of .
The iodine-stabilized laser can be used for various applications including
interferometric measurements
Absolute frequency measurements and hyperfine structures of the molecular iodine transitions at 578 nm
We report absolute frequency measurements of 81 hyperfine components of the
rovibrational transitions of molecular iodine at 578 nm using the second
harmonic generation of an 1156-nm external-cavity diode laser and a fiber-based
optical frequency comb. The relative uncertainties of the measured absolute
frequencies are typically . Accurate hyperfine constants of
four rovibrational transitions are obtained by fitting the measured hyperfine
splittings to a four-term effective Hamiltonian including the electric
quadrupole, spin-rotation, tensor spin-spin, and scalar spin-spin interactions.
The observed transitions can be good frequency references at 578 nm, and are
especially useful for research using atomic ytterbium since the transitions are
close to the clock transition of ytterbium
Dual-Mode Operation of an Optical Lattice Clock Using Strontium and Ytterbium Atoms
We have developed an optical lattice clock that can operate in dual modes: a
strontium (Sr) clock mode and an ytterbium (Yb) clock mode. Dual-mode operation
of the Sr-Yb optical lattice clock is achieved by alternately cooling and
trapping Sr and Yb atoms inside the vacuum chamber of the clock.
Optical lattices for Sr and Yb atoms were arranged with horizontal and vertical
configurations, respectively, resulting in a small distance of the order of 100
m between the trapped Sr and Yb atoms. The S-P
clock transitions in the trapped atoms were interrogated in turn and the clock
lasers were stabilized to the transitions. We demonstrated the frequency ratio
measurement of the Sr and Yb clock transitions by using the dual-mode operation
of the Sr-Yb optical lattice clock. The dual-mode operation can reduce the
uncertainty of the blackbody radiation shift in the frequency ratio
measurement, because both Sr and Yb atoms share the same blackbody radiation.Comment: 6 pages,5 figure
Frequency ratio measurement of 171Yb and 87Sr optical lattice clocks
The frequency ratio of the 1S0(F=1/2)-3P0(F=1/2) clock transition in 171Yb
and the 1S0(F=9/2)-3P0(F=9/2) clock transition in 87Sr is measured by an
optical-optical direct frequency link between two optical lattice clocks. We
determined the ratio (\nu_{Yb}/\nu_{Sr}) to be 1.207 507 039 343 340 4(18) with
a fractional uncertainty of 1.5x10^{-15}. The measurement uncertainty of the
frequency ratio is smaller than that obtained from absolute frequency
measurements using the International Atomic Time (TAI) link. The measured ratio
agrees well with that derived from the absolute frequency measurement results
obtained at NIST and JILA, Boulder, CO using their Cs-fountain clock. Our
measurement enables the first international comparison of the frequency ratios
of optical clocks, and we obtained a good agreement between the two measured
ratios with an uncertainty smaller than the TAI link. The measured frequency
ratio will be reported to the International Committee for Weights and Measures
for a discussion related to the redefinition of the second.Comment: accepted for publication in Opt. Express. 8 pages, 3 figures, 1 tabl
Improved frequency measurement of the - clock transition in Sr using the Cs fountain clock at NMIJ as a transfer oscillator
We performed an absolute frequency measurement of the -
transition in Sr with a fractional uncertainty of ,
which is less than one third that of our previous measurement. A caesium
fountain atomic clock was used as a transfer oscillator to reduce the
uncertainty of the link between a strontium optical lattice clock and the SI
second. The absolute value of the transition frequency is 429 228 004 229
873.56(49) Hz.Comment: accepted for publication in Journal of the Physical Society of Japan,
7 pages, 2 figure
Demonstration of the nearly continuous operation of an Yb optical lattice clock for half a year
Optical lattice clocks surpass primary Cs microwave clocks in frequency
stability and accuracy, and are promising candidates for a redefinition of the
second in the International System of Units (SI). However, the robustness of
optical lattice clocks has not yet reached a level comparable to that of Cs
fountain clocks which contribute to International Atomic Time (TAI) by the
nearly continuous operation. In this paper, we report the long-term operation
of an Yb optical lattice clock with a coverage of 80.3% for half a year
including uptimes of 93.9% for the first 24 days and 92.6% for the last 35
days. This enables a nearly dead-time-free frequency comparison of the optical
lattice clock with TAI over months, which provides a link to the SI second with
an uncertainty of low . By using this link, the absolute frequency of
the SP clock transition of Yb is measured as 518
295 836 590 863.54(26) Hz with a fractional uncertainty of .
This value is in agreement with the recommended frequency of Yb as a
secondary representation of the second