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1.
Design and test of the microwave cavity in an optically-pumped Rubidium beam frequency standard 下载免费PDF全文
We are developing a compact rubidium atomic beam frequency standard with optical pumping and detection.The cavity for microwave interrogation is an important part of the clock.The cavity in our design is a Ramsey-type,E-bend one,which is the same as the conventional method in most cesium beam clocks.Requirements for the design are proposed based on the frequency shift associated with the cavity.The basic structure of the cavity is given by theoretical analysis and detailed dimensions are determined by means of electromagnetic field simulation with the help of commercial software.The cavity is manufactured and fabricated successfully.The preliminary test result of the cavity is given,which is in good agreement with the simulation.The resonant frequency is 6.835 GHz,equal to the clock transition frequency of87Rb,and the loaded quality factor is 500.These values are adjustable with posts outside the cavity.Estimations on the Ramsey line width and several frequency shifts are made. 相似文献
2.
For ultra-high resolution spectroscopic applications such as optical frequency standards, the value of thermal sources such as atomic beams is currently limited by secondorder Doppler broadening. The use of a longitudinal interaction geometry in which an atomic beam crosses the counter-propagating laser fields at a small angle is able to reduce second-order Doppler broadening to an insignificant level as well as to provide long interaction times without the necessity of large-diameter optical beams. We have analyzed this geometry for the case of the long-lived calcium intercombination line, and conclude that when combined with pulsed (Ramsey) excitation, the longitudinal interaction geometry could be used with a thermal calcium beam to create an optical frequency standard with a reproducibility of the order of 10?14 for a few seconds averaging time. Our initial experimental results have demonstrated the first use of the longitudinal geometry. 相似文献
3.
钙离子光频标是原子光频标的成员之一。中国科学院精密测量科学与技术创新研究院(原武汉物理与数学研究所)从2000年开始选择钙离子为研究体系,先后解决了单离子稳定囚禁与有效冷却、超窄线宽激光稳频等一系列关键问题,特别是一步步抑制微运动和黑体辐射效应,实现了不确定度3.0×10-18的液氮低温离子光频标和不确定度4.8×10-18的室温离子光频标,稳定度达到6.3×10-18@52万秒。通过集成化设计,实现了不确定度1.3×10-17、高鲁棒性的可搬运钙离子光钟,并基于该光钟实现了高程差测量应用。通过参考本地铯喷泉钟和本地时标,并远程溯源到国际秒定义,实现了不确定度达3.2×10-16的钙离子光频跃迁绝对频率测量。钙离子光频跃迁被国际计量局推荐为新增的次级秒定义参考。 相似文献
4.
Vogel KR Diddams SA Oates CW Curtis EA Rafac RJ Itano WM Bergquist JC Fox RW Lee WD Wells JS Hollberg L 《Optics letters》2001,26(2):102-104
With a fiber-broadened, femtosecond-laser frequency comb, the 76-THz interval between two laser-cooled optical frequency standards was measured with a statistical uncertainty of 2x10(-13) in 5 s , to our knowledge the best short-term instability thus far reported for an optical frequency measurement. One standard is based on the calcium intercombination line at 657 nm, and the other, on the mercury ion electric-quadrupole transition at 282 nm. By linking this measurement to the known Ca frequency, we report a new frequency value for the Hg(+) clock transition with an improvement in accuracy of ~10(5) compared with its best previous measurement. 相似文献
5.
Yakabe M Nito K Yoshida M Nakazawa M Koga Y Hagimoto K Ikegami T 《Optics letters》2005,30(12):1512-1514
We describe an ultrastable cesium (Cs) atomic clock with a 9.1926-GHz regeneratively mode-locked fiber laser obtained by use of an optically pumped Cs beam tube. By adopting a 1-m-long Cs beam tube with a linewidth of 110 Hz, we have successfully obtained frequency stabilities of 4.8 x 10(-12) for tau = 1 s and 6.3 x 10(-13) for tau = 50 s for a 9.1926-GHz microwave output signal. This Cs atomic clock can generate an optical pulse train with the same stability as that of the obtained microwave, which allows us to deliver a frequency standard optical signal throughout the world by means of optical fiber networks. 相似文献
6.
Ludlow AD Huang X Notcutt M Zanon-Willette T Foreman SM Boyd MM Blatt S Ye J 《Optics letters》2007,32(6):641-643
We demonstrate phase and frequency stabilization of a diode laser at the thermal noise limit of a passive optical cavity. The system is compact and exploits a cavity design that reduces vibration sensitivity. The subhertz laser is characterized by comparison with a second independent system with similar fractional frequency stability (1x10(-15) at 1 s). The laser is further characterized by resolving a 2 Hz wide, ultranarrow optical clock transition in ultracold strontium. 相似文献
7.
《Revue Generale de Thermique》1998,37(1):49-59
We have developed optical techniques for thermal characterisation at micrometric scale based upon the detection and the analysis of the modifications of a reflected laser beam. The modifications are induced by a well controlled thermal excitation originating from electric heating. According to this principle we have developed a very compact, high sensitivity and high resolution optical bench. It includes a homodyne stabilised Michelson interferometer, a reflectometer and a differential interferometer. It is capable of detecting a temperature variation as small as 10−3 K and a thermal dilatation as small as 10−15 m. It has a large bandwidth ranging from DC to 125 MHz. The optical bench also includes a microscope and a visualisation system allowing analysis at micrometric scale.In the field of thermal studies in microelectronics, we have been able to determine the temperature of running microelectronic components in order to estimate their quality and reliability, to study the temperature distribution and to detect hot spots in integrated circuits and to study thermooptical and thermophysical properties of materials used in microelectronics. 相似文献
8.
An optical clock based on an Er3+ fiber femtosecond laser and a two-mode He–Ne/CH4 optical frequency standard (λ=3.39 μm) is realized. Difference-frequency generation is used to down convert the 1.5-μm frequency comb of the Er3+ femtosecond laser to the 3.4-μm range. The generated infrared comb overlaps with the He–Ne/CH4 laser wavelength and does not depend on the carrier–envelope offset frequency of the 1.5-μm comb. In this way a direct phase-coherent
connection between the optical frequency of the He–Ne/CH4 standard and the radio frequency pulse repetition rate of the fiber laser is established. The stability of the optical clock
is measured against a commercial hydrogen maser. The measured relative instability is 1×10−12 at 1 s and for averaging times less than 50 s it is determined by the microwave standard, while for longer times a drift
of the He–Ne/CH4 optical standard is dominant. 相似文献
9.
时间频率基准装置——铯原子喷泉钟, 在标准时间产生和保持、基础物理研究中发挥了重要的作用. 介绍了铯原子喷泉钟的工作原理, 对影响其性能的各项噪声源和频移项给出了分析, 影响频率稳定度性能的主要因素为Dick 效应相关的原子团装载时间、微波激励源相位噪声和探测激光的频率噪声, 影响频率不确定性能主要频移项为: 黑体辐射频移、冷原子碰撞频移、腔相位分布频移和微波泄露频移; 总结和比较了当前具有先进性能的铯原子喷泉钟采用的技术; 介绍了铯原子喷泉钟的主要应用方向、空间冷原子铯钟的研制情况和光学频率原子钟进展. 相似文献
10.
11.
We report observation of high contrast Raman-Ramsey fringes using time delayed optical pulse pairs in a rubidium vapor cell. The width of these fringes are not limited by saturation and provides a simpler means to produce narrow atomic linewidths using a thermal vapor medium for compact atomic clock applications. We also demonstrate phase-scanned Raman-Ramsey fringes, with potential application to sensitive detection of trace vapors. 相似文献
12.
13.
Corwin KL Thomann I Dennis T Fox RW Swann W Curtis EA Oates CW Wilpers G Bartels A Gilbert SL Hollberg L Newbury NR Diddams SA Nicholson JW Yan MF 《Optics letters》2004,29(4):397-399
A frequency comb is generated with a chromium-doped forsterite femtosecond laser, spectrally broadened in a dispersion-shifted highly nonlinear fiber, and stabilized. The resultant evenly spaced comb of frequencies ranges from 1.1 to beyond 1.8 microm. The frequency comb was referenced simultaneously to the National Institute of Standards and Technology's optical frequency standard based on neutral calcium and to a hydrogen maser that is calibrated by a cesium atomic fountain clock. With this comb we measured two frequency references in the telecommunications band: one half of the frequency of the d/f crossover transition in 87Rb at 780 nm, and the methane v2 + 2v3 R(8) line at 1315 nm. 相似文献
14.
The design and experimental results of an optical clock distribution system based on integrated free-space micro-optics are reported. Planar optical components such as lenses, beamsplitters, and mirrors, are monolithically integrated on a single glass substrate to provide a stable and compact system. A single input beam is split and distributed evenly to N output positions using a binary tree of beamsplitters. The experiment shown demonstrates the principle idea for a system with a fanout of eight. Theoretical considerations show that a fanout of 64 or larger is feasible. 相似文献
15.
Wilpers G. Degenhardt C. Binnewies T. Chernyshov A. Riehle F. Helmcke J. Sterr U. 《Applied physics. B, Lasers and optics》2003,76(2):149-156
We have investigated the two major effects that limit the accuracy of an optical frequency standard based on laser-cooled
neutral calcium atoms, i.e. the residual Doppler shift and atomic collisions. A new correction method was applied to reduce
the contribution of the residual Doppler effect to the total fractional uncertainty to 1×10-14. Measurements of the shift of the clock transition frequency due to cold collisions allowed us to reduce their contribution
to 4×10-15. With these improvements we have reduced the total fractional frequency uncertainty of the standard by nearly an order of
magnitude to 2×10-14.
Received: 9 August 2002 / Revised version: 16 November 2002 / Published online: 26 February 2003
RID="*"
ID="*"Permanent address: Russian Academy of Sciences, P.N. Lebedev Physical Institute, Samara Branch, Novo-Sadovaya st. 221,
Samara 443011, Russia
RID="**"
ID="**"Corresponding author. Fax: +49-531/592-4305, E-mail: uwe.sterr@ptb.de 相似文献
16.
L. S. Pan H. P. Lee C. Lu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,50(1):27-33
We report the synthesis and measurement of an
ultra-precise and extremely stable optical frequency in the
telecommunications window around 1543 nm. Using a fibre-based femtosecond
frequency comb we have phase-stabilised a fibre laser at 194 THz to an
optical frequency standard at 344 THz, thus transferring the properties of
the optical frequency standard to another spectral region. Relative to the
optical frequency standard, the synthesised frequency at 194 THz is
determined to within 1 mHz and its fractional frequency instability is
measured to be less than 2×10-15 at 1 s, reaching 5×
10-18 after 8000 s. We also measured the synthesised frequency against
a caesium fountain clock: here the frequency comparison itself contributes
less than 4 mHz (2×10-17) to the uncertainty. Our results
confirm the suitability of fibre based frequency comb technology for
precision measurements and frequency synthesis, and enable long-distance
comparison of optical clocks by using optical fibres to transmit the
frequency information. 相似文献
17.
A novel experimental configuration for thermal lens detection is described. The method makes use of optical filtering of the probe beam by means of a circular aperture. This considerably reduces noise associated with intensity fluctuations of the probe beam. The technique provides an enhancement of the signal-to-noise ratio by almost one order of magnitude as compared to other thermal lens laser spectrometers. A theoretical calculation of the signal enhancement associated with optical filtering of the probe beam is presented. Furthermore, experiments on methyl blue dissolved in ethylalcohol are described which verify the theoretical predictions. 相似文献
18.
A diode-laser optical frequency standard based on laser-cooled Ca atoms: Sub-kilohertz spectroscopy by optical shelving detection 总被引:2,自引:0,他引:2
C.W. Oates F. Bondu R.W. Fox L. Hollberg 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(3):449-460
We report an optical frequency standard at 657 nm based on laser-cooled/trapped Ca atoms. The system consists of a novel,
compact magneto-optic trap which uses 50 mW of frequency-doubled diode laser light at 423 nm and can trap >107 Ca atoms in 20 ms. High resolution spectroscopy on this atomic sample using the narrow 657 nm intercombination line resolves
linewidths (FWHM) as narrow as 400 Hz, the natural linewidth of the transition. The spectroscopic signal-to-noise ratio is
enhanced by an order of magnitude with the implementation of a “shelving" detection scheme on the 423 nm transition. Our present
apparatus achieves a fractional frequency instability of in 1 s with a potential atom shot-noise-limited performance of and excellent prospects for high accuracy.
Received 2 November 1998 相似文献
19.
We propose and realize a new optical state selection method on a cesium atomic fountain clock by applying a two-laser 3-3' optical pumping configuration to spin polarize atoms. The atoms are prepared in |F=3, mF=0> clock state with optical pumping directly after being launched up, followed by a pushing beam to push away the atoms remaining in the |F=4> state. With a state selection efficiency exceeding 92%, this optical method can substitute the traditional microwave state selection, and helps to develop a more compact physical package. A Ramsey fringe has been achieved with this optical state selection method, and a contrast of 90% is obtained with a full width half maximum of 0.92 Hz. The short-term frequency stability of 6.8×10-14 (τ/s)-1/2 is acquired. In addition, the number of detected atoms is increased by a factor of 1.7 with the optical state selection. 相似文献
20.
An optical clockwork is created with a compact 1-GHz repetition-rate laser and three nonlinear crystals. The broadband continuum output of the laser covers sufficient bandwidth to provide direct access to its carrier-envelope offset frequency without the use of a microstructure fiber. We phase lock the femtosecond comb to a Ca optical standard and monitor the stability of the repetition rate, f(r) , at 1 GHz. We demonstrate that the short-term stability of the microwave output of the optical clock is at least as good as that of a high-performance hydrogen maser. 相似文献