251 research outputs found
Mid-IR frequency measurement using an optical frequency comb and a long-distance remote frequency reference
We have built a frequency chain which enables to measure the absolute
frequency of a laser emitting in the 28-31 THz frequency range and stabilized
onto a molecular absorption line. The set-up uses an optical frequency comb and
an ultrastable 1.55 m frequency reference signal, transferred from
LNE-SYRTE to LPL through an optical link. We are now progressing towards the
stabilization of the mid-IR laser via the frequency comb and the extension of
this technique to quantum cascade lasers. Such a development is very
challenging for ultrahigh resolution molecular spectroscopy and fundamental
tests of physics with molecules
Phase noise characterization of sub-hertz linewidth lasers via digital cross correlation
Phase noise or frequency noise is a key metrics to evaluate the short term
stability of a laser. This property is of a great interest for the applications
but delicate to characterize, especially for narrow line-width lasers. In this
letter, we demonstrate a digital cross correlation scheme to characterize the
absolute phase noise of sub-hertz line-width lasers. Three 1,542 nm
ultra-stable lasers are used in this approach. For each measurement two lasers
act as references to characterize a third one. Phase noise power spectral
density from 0.5 Hz to 0.8 MHz Fourier frequencies can be derived for each
laser by a mere change in the configuration of the lasers. This is the first
time showing the phase noise of sub-hertz line-width lasers with no reference
limitation. We also present an analysis of the laser phase noise performance.Comment: 4 pages, 5 figure
Accuracy Evaluation of an Optical Lattice Clock with Bosonic Atoms
We report the first accuracy evaluation of an optical lattice clock based on
the 1S0 - 3P0 transition of an alkaline earth boson, namely 88Sr atoms. This
transition has been enabled using a static coupling magnetic field. The clock
frequency is determined to be 429 228 066 418 009(32) Hz. The isotopic shift
between 87Sr and 88Sr is 62 188 135 Hz with fractional uncertainty 5.10^{-7}.
We discuss the conditions necessary to reach a clock accuracy of 10^{-17} or
less using this scheme.Comment: 3 pages, 4 figures, uses ol.sty fil
Guidelines for developing optical clocks with fractional frequency uncertainty
There has been tremendous progress in the performance of optical frequency
standards since the first proposals to carry out precision spectroscopy on
trapped, single ions in the 1970s. The estimated fractional frequency
uncertainty of today's leading optical standards is currently in the
range, approximately two orders of magnitude better than that of the best
caesium primary frequency standards. This exceptional accuracy and stability is
resulting in a growing number of research groups developing optical clocks.
While good review papers covering the topic already exist, more practical
guidelines are needed as a complement. The purpose of this document is
therefore to provide technical guidance for researchers starting in the field
of optical clocks. The target audience includes national metrology institutes
(NMIs) wanting to set up optical clocks (or subsystems thereof) and PhD
students and postdocs entering the field. Another potential audience is
academic groups with experience in atomic physics and atom or ion trapping, but
with less experience of time and frequency metrology and optical clock
requirements. These guidelines have arisen from the scope of the EMPIR project
"Optical clocks with uncertainty" (OC18). Therefore, the
examples are from European laboratories even though similar work is carried out
all over the world. The goal of OC18 was to push the development of optical
clocks by improving each of the necessary subsystems: ultrastable lasers,
neutral-atom and single-ion traps, and interrogation techniques. This document
shares the knowledge acquired by the OC18 project consortium and gives
practical guidance on each of these aspects
Quantum cascade laser frequency stabilisation at the sub-Hz level
Quantum Cascade Lasers (QCL) are increasingly being used to probe the
mid-infrared "molecular fingerprint" region. This prompted efforts towards
improving their spectral performance, in order to reach ever-higher resolution
and precision. Here, we report the stabilisation of a QCL onto an optical
frequency comb. We demonstrate a relative stability and accuracy of 2x10-15 and
10-14, respectively. The comb is stabilised to a remote near-infrared
ultra-stable laser referenced to frequency primary standards, whose signal is
transferred via an optical fibre link. The stability and frequency traceability
of our QCL exceed those demonstrated so far by two orders of magnitude. As a
demonstration of its capability, we then use it to perform high-resolution
molecular spectroscopy. We measure absorption frequencies with an 8x10-13
relative uncertainty. This confirms the potential of this setup for ultra-high
precision measurements with molecules, such as our ongoing effort towards
testing the parity symmetry by probing chiral species
Guidelines for developing optical clocks with 10-18 fractional frequency uncertainty
There has been tremendous progress in the performance of optical frequency standards since the first proposals to carry out precision spectroscopy on trapped, single ions in the 1970s. The estimated fractional frequency uncertainty of today's leading optical standards is currently in the 10−18 range, approximately two orders of magnitude better than that of the best caesium primary frequency standards. This exceptional accuracy and stability is resulting in a growing number of research groups developing optical clocks. While good review papers covering the topic already exist, more practical guidelines are needed as a complement. The purpose of this document is therefore to provide technical guidance for researchers starting in the field of optical clocks. The target audience includes national metrology institutes (NMIs) wanting to set up optical clocks (or subsystems thereof) and PhD students and postdocs entering the field. Another potential audience is academic groups with experience in atomic physics and atom or ion trapping, but with less experience of time and frequency metrology and optical clock requirements. These guidelines have arisen from the scope of the EMPIR project "Optical clocks with 1×10−18 uncertainty" (OC18). Therefore, the examples are from European laboratories even though similar work is carried out all over the world. The goal of OC18 was to push the development of optical clocks by improving each of the necessary subsystems: ultrastable lasers, neutral-atom and single-ion traps, and interrogation techniques. This document shares the knowledge acquired by the OC18 project consortium and gives practical guidance on each of these aspects.EU/Horizon2020/EMPIR/E
Femtosecond laser-based optical frequency combs for frequency metrology
International audienc
Femtosecond laser-based optical frequency combs for frequency metrology
International audienc
Femtosecond laser-based optical frequency combs for frequency metrology
International audienc
- …