Spectral purity transfer
between optical wavelengths
-18
at the 10 level
Daniele Nicolodi1, Bérengère Argence1, Wei Zhang1,
Rodolphe Le Targat1, Giorgio Santarelli1,2, and Yann Le Coq1
1 LNE-SYRTE,
Observatoire de Paris, CNRS, UPMC
2 LP2N, CNRS, IOGS, Université Bordeaux I, Université de Bordeaux 1
‣
Laser frequency stabilization via high-finesse optical cavities
is limited by thermal noise at the 10-16 fractional frequency
stability level.
‣
Laser frequency stabilization via high-finesse optical cavities
is limited by thermal noise at the 10-16 fractional frequency
stability level.
‣
Some applications would benefit from higher stability:
- optical lattice clocks,
- low phase-noise microwave generation,
- fundamental physics tests, ...
‣
Laser frequency stabilization via high-finesse optical cavities
is limited by thermal noise at the 10-16 fractional frequency
stability level.
‣
Some applications would benefit from higher stability:
- optical lattice clocks,
- low phase-noise microwave generation,
- fundamental physics tests, ...
‣
Improvement requires substantially more complex setups:
- longer cavities,
- cryogenic temperature,
- mono-crystalline cavities,
- crystalline high-reflectivity coatings.
‣
Laser frequency stabilization via high-finesse optical cavities
is limited by thermal noise at the 10-16 fractional frequency
stability level.
‣
Some applications would benefit from higher stability:
- optical lattice clocks,
- low phase-noise microwave generation,
- fundamental physics tests, ...
‣
Improvement requires substantially more complex setups:
- longer cavities,
- cryogenic temperature,
- mono-crystalline cavities,
- crystalline high-reflectivity coatings.
‣
Or completely different approaches:
- laser frequency stabilization via spectral hole burning
promises stabilities in the 10-17 range or lower.
‣
Improving the state-of-the-art optical cavity laser frequency
stabilization requires complex setups, some techniques are
limited to work at implementation specific wavelengths.
‣
Improving the state-of-the-art optical cavity laser frequency
stabilization requires complex setups, some techniques are
limited to work at implementation specific wavelengths.
‣
Techniques to transfer frequency stability to lasers at
different wavelengths without degradation are highly
desirable.
‣
Improving the state-of-the-art optical cavity laser frequency
stabilization requires complex setups, some techniques are
limited to work at implementation specific wavelengths.
‣
Techniques to transfer frequency stability to lasers at
different wavelengths without degradation are highly
desirable.
‣
We present a optical frequency comb based solution for
frequency stability transfer between a 1062 nm laser and a
1542 nm laser, contributing fractional frequency instability
of 3 × 10-18 at one second.
f˜m = νm − Nm frep − fo
f˜s = νs − Ns frep − fo
f˜m = νm − Nm frep − fo
fm = νm − Nm frep
fs = νs − Ns frep
f˜s = νs − Ns frep − fo
f˜m = νm − Nm frep − fo
fm = νm − Nm frep
∗
fm
∗
fs
= fm /Nm
= fs /Ns
fs = νs − Ns frep
f˜s = νs − Ns frep − fo
Mm /Ms = Nm /Ns
Nm /Ns � νm /νs
f˜m = νm − Nm frep − fo
fm = νm − Nm frep
∗
fm
= fm /Nm
∗
fs
= fs /Ns
fs = νs − Ns frep
f˜s = νs − Ns frep − fo
Mm /Ms = Nm /Ns
Nm /Ns � νm /νs
∗
∗
f∆
= fm
− fs∗
optical frequency comb
locked in the narrow
linewidth regime
limited optical power
low signal to noise ratio
detection limited
tracking in 10 kHz bandwidth
both beat-notes derived
from the same optical branch
common mode optical phase noise
frequency stability
transfer characterization
beat the slave laser with
a reference ultra-stable laser
slave vs reference laser beat-note fractional frequency stability
master laser stability: 4.5 × 10-16 at 1 s
reference laser stability: 5.0 × 10-16 at 1 s
pre-stabilized slave laser
phase-locked to master laser
6.7 × 10-16
slave vs reference laser beat-note fractional frequency stability
master laser stability: 4.5 × 10-16 at 1 s
reference laser stability: 5.0 × 10-16 at 1 s
pre-stabilized slave laser
phase-locked to master laser
6.7 × 10-16
measured fractional frequency stability is compatible with
spectral purity transfer without stability degradation.
spectral purity transfer phase
noise limit characterization
comparison of the phase difference measurement
obtained by two quasi-identical setups monitoring
the same master and slave lasers
phase noise limit from differential phase measurement
low frequency noise excess
below ~1 Hz
trackers “servo bump”
signal-to-noise ratio limit
frequency stability transfer limit from differential phase measurement
modified Allan deviation
3 × 10–18
2 × 10–20
frequency stability transfer limit from differential phase measurement
modified Allan deviation
3 × 10–18
2 × 10–20
lowest reported optical frequency comb
system short and long term stability
‣
The single optical branch setup is effective in suppressing
the phase fluctuations introduced in the EDFA and HNLF
up to terms scaling linearly with wavelength.
‣
We demonstrated a fiber based optical frequency comb
solution capable of frequency stability transfer
contributing 3 × 10-18 fractional instability at one second
factor of 20 improvement over published results.
‣
The 2 × 10-20 stability at 1000 s is the lowest reported long
term stability for optical frequency comb systems.
‣
Narrow linewidth locking of the comb is required. If neither
the master or the slave laser are at the com’s central
wavelength a third stable laser is required.
‣
The slave laser must be pre-stabilized to a linewidth much
smaller than the trackers’ bandwidths
stabilization on fiber spool delay lines is a possibility.
‣
The solution can be readily applied to any laser in the 1 µm
to 2 µm wavelength region. It can be extended to the
visible region through frequency doubling.
noise sources identification
and characterization
testing interferometer
and optical fiber noise canceling setup
phase noise from different configurations
PRELIMINARY
low frequency noise matches
comb’s phase noise limit
unknown peaks
probably due to laser noise
‣
The low phase noise excess measured in the optical
spectral purity transfer at low frequency is compatible with
technical sources of noise
optical frequency comb
phase fundamental noise is not the current limit.
‣
Adding 5 m of uncompensated optical fiber to the
interferometer setup does not affect the phase noise
phase noise is due to residual optical fibers noise.
‣
Evidence hints at amplitude-noise to phase-noise
conversion in the photodiodes as a possible relevant
phase noise source.
‣
We demonstrate a fiber based optical frequency comb
solution capable of frequency stability transfer contributing
3 × 10-18 fractional instability at one second averaging
down to 2 × 10-20 stability in 1000 seconds.
‣
The phase stability of the optical frequency comb is not the
current limiting factor in the phase noise performance. We
are working on identification and characterization of the
phase noise sources
‣
We hope to exploit the demonstrated performances putting
to good use an hyper-stable laser obtained via the spectral
hole burning technique.
‣
We demonstrate a fiber based optical frequency comb
solution capable of frequency stability transfer contributing
3 × 10-18 fractional instability at one second averaging
down to 2 × 10-20 stability in 1000 seconds.
‣
The phase stability of the optical frequency comb is not the
current limiting factor in the phase noise performance. We
are working on identification and characterization of the
phase noise sources
‣
We hope to exploit the demonstrated performances putting
to good use an hyper-stable laser obtained via the spectral
hole burning technique.
Thanks for your attention. Questions?