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51.
Ultra-Stable Rubidium-Stabilized External-Cavity Diode Laser Based on the Modulation Transfer Spectroscopy Technique
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We construct an ultra-stable external-cavity diode laser via modulation transfer spectroscopy referencing on a hyperfine component of the ST Rb D2 lines at 780 nm. The Doppler-free dispersion-like modulation transfer signal is obtained with high signal-to-noise-ratio. The instability of the laser frequency is measured by beating with an optical frequency comb which is phase-locked to an ultra-stable oven controlled crystal oscillator. The Allan deviation is 3.9 × 10-13 at I s averaging time and 9.8 ×10-14 at 90s averaging time. 相似文献
52.
Stabilization and Shift of Frequency in an External Cavity Diode Laser with Solenoid-Assisted Saturated Absorption
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A simple method to realize both stabilization and shift of the frequency in an external cavity diode laser (ECDL) is reported. Due to the Zeeman effect, the saturated absorption spectrum of Rb atoms in a magnetic field is shifted. This shift can be used to detune the frequency of the ECDL, which is locked to the saturated absorption spectrum. The frequency shift amount can be controlled by changing the magnetic field for a specific polarization state of the laser beam. The advantages of this tunable frequency lock include low laser power requirement, without additional power loss, cheapness, and so on. 相似文献
53.
A Group-Period Phase Comparison Method Based on Equivalent Phase Comparison Frequency 总被引:2,自引:0,他引:2
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Based on the principle of equivalent phase comparison frequency, we propose a group-period phase comparison method. This method can be used to reveal the inherent relations between periodic signals and the change laws of the phase difference. If these laws are applied in the processing of the mutual relations between frequency signals, phase comparison can be accomplished without frequency normalization. Experimental results show that the method can enhance the measurement resolution to 10-13/s in the time domain. 相似文献
54.
O. Lopez A. Amy-Klein C. Daussy C. Chardonnet F. Narbonneau M. Lours G. Santarelli 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(1):35-41
RF frequency transfer over an urban 86 km fibre has
been demonstrated with a resolution of 2×10-18 at one day
measuring time using an optical compensator. This result is obtained with a
reference carrier frequency of 1 GHz, and a rapid scrambling of the
polarisation state of the input light in order to reduce the sensitivity to
the polarisation mode dispersion in the fibre. The limitation due to the
fibre chromatic dispersion associated with the laser frequency fluctuations
is highlighted and analyzed. A preliminary test of an extended compensated
link over 186 km using optical amplifiers gives a resolution below
10-17 at 1 day. 相似文献
55.
P. Balling P. Křen 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(1):3-10
This paper describes the results of absolute frequency
measurements of primary wavelength standards 633 nm, 543 nm, 532 nm, (iodine
stabilized) and 1540 nm (acetylene stabilized) in CMI. The values obtained
with Menlo Systems femtosecond frequency comb in CMI are compared with
previous measurements of the same standards in BIPM, BEV and MPQ. Measured
sub-Doppler linewidths and relative intensities of several hyperfine
spectral components of iodine molecule are also presented. 相似文献
56.
Ye.S. Golubeva W. Cassing L.A. Kondratyuk 《The European Physical Journal A - Hadrons and Nuclei》2002,14(2):255-263
We study the perspectives of resonant and nonresonant charmed-meson production in ˉp + A reactions within the Multiple Scattering Monte Carlo (MSMC) approach. We calculate the production of the resonances Ψ(3770),Ψ(4040)
and Ψ(4160) on various nuclei, their propagation and decay to D,ˉD, D
*,ˉD*, D
s,ˉDs in the medium and vacuum, respectively. The modifications of the open charm vector mesons in the nuclear medium are found
to be rather moderate or even small such that dilepton spectroscopy will require an invariant mass resolution of a few MeV.
Furthermore, the elastic and inelastic interactions of the open charm mesons in the medium are taken into account, which can
be related to (u, d )-, s- or c-quark exchange with nucleons. It is found that by studying the D/ˉD ratio for low momenta in the laboratory ( ? 2 - 2.2 GeV/c) as a function of the target mass A stringent constraints on the c-quark exchange cross-section can be obtained. On the other hand, the ratios D
-
s/D
+
s as well as D/D
-
s and D/D
+
s at low momenta as a function of A will permit to fix independently the strength of the s-quark exchange reaction in D
-
s
N scattering.
Received: 1 March 2002 / Accepted: 21 March 2002 相似文献
57.
S. Mukhopadhyay M. Saglam A. Chatterjee 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,59(1):69-73
A fresh and critical look has been given to the long-time
behaviour of the quantum diffusion problem and a marginally more
accurate solution has been obtained as compared to the one
reported in the recent literature. Attempt has also been made to
bring out a few interesting generic features of this problem which
may have important bearing on real systems in the quantum domain. 相似文献
58.
Cyril Drag 《Optics Communications》2007,275(1):190-195
A two-colour laser technique is developed for photodetachment microscopy, by means of microwave modulation of a CW single-mode dye laser. A phase modulation regime is achieved through an electro-optical LiNbO3 crystal excited at the frequency 1.95 GHz. The two first sidebands created are selected by rejection of the other orders through a plane Fabry-Perot interferometer. With the resulting two-colour radiation, the photodetachment microscopy technique is applied to a beam of 32S− ions. It is shown that the superposition of the two resulting interference patterns can be used as a ‘spectral vernier’ to remove the uncertainty on the electric field and absolute energy scale. Without any initial assumption on the value F of the electric field in the laser-ion interaction region, a measure of F and of the electron affinity eA of Sulfur can be obtained. Putting 16 recordings of two-colour photodetachment interferograms together, with the only condition that F be the same for all experiments, one gets eA(32S) = 16752.978(11) cm−1, which is quite compatible, even though not as accurate, with the most recently recommended value eA(32S) = 16752.9760(42) cm−1. A proposal is made for going from an incoherent to a coherent two-colour photodetachment scheme, which would make photodetachment interferograms sensitive to a new degree of freedom. 相似文献
59.
R. Nicodemus S. Grossmann Martin Holthaus 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,10(2):385-396
We examine the background flow variational principle for calculating bounds on the energy dissipation rate in turbulent shear
flow, and suggest to select this principle's test functions such that they comply with the small-scale smoothness of real
turbulent velocity fields. A self-consistent algorithm implementing this requirement then yields an upper bound on the dimensionless
dissipation coefficient which shows a weak power-law decrease at high Reynolds numbers, instead of approaching a nonzero constant,
as it did in previous estimates.
Received 26 October 1998 相似文献
60.
Geo-reactor models suggest the existence of natural nuclear reactors at different deep-earth locations with loosely defined output power. Reactor fission products undergo beta decay with the emission of electron antineutrinos, which routinely escape the earth. Neutrino mixing distorts the energy spectrum of the electron antineutrinos. Characteristics of the distorted spectrum observed at the earth's surface could specify the location of a geo-reactor, discriminating the models and facilitating more precise power measurement. 相似文献