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A diode laser spectrometer at 634nm and absolute frequency measurements using optical frequency comb 下载免费PDF全文
This paper reports that two identical external-cavity-diode-laser
(ECDL) based spectrometers are constructed at 634 nm referencing on
the hyperfine B-X transition R(80)8-4 of 127I2. The lasers
are stabilized on the Doppler-free absorption signals using the
third-harmonic detection technique. The instability of the
stabilized laser is measured to be 2.8×10-12 (after
1000 s) by counting the beat note between the two lasers. The
absolute optical frequency of the transition is, for the first time,
determined to be 472851936189.5 kHz by using an optical frequency
comb referenced on the microwave caesium atomic clock. The
uncertainty of the measurement is less than 4.9 kHz. 相似文献
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椭圆面积公式S=πab,其中π为圆周率,a、b分别是椭圆半短轴、半长轴的长.关于椭圆面积公式的证法有多种,文献[1]利用仿射变换与仿射不变量推导出椭圆面积公式,文献[2]通过对单位正方形的拉伸(压缩)变换前后面积关系的讨论,给出了椭圆面积公式的又一证法.文献[3]利用初等数学的方法,推导出椭圆面积的计算公式.本文利用投影和定积分知识相结合的方法,给出了任意曲边形面积公式,进而给出椭圆面积公式的一种新的证法. 相似文献
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Thermoelectrics has long been considered as a promising way of power generation for the next decades. So far,extensive efforts have been devoted to the search of ideal thermoelectric materials, which require both high electrical conductivity and low thermal conductivity. Recently, the emerging Dirac semimetal Cd3As2, a three-dimensional analogue of graphene, has been reported to host ultra-high mobility and good electrical conductivity as metals. Here, we report the observation of unexpected low thermal conductivity in Cd3As2, one order of magnitude lower than the conventional metals or semimetals with a similar electrical conductivity, despite the semimetal band structure and high electron mobility. The power factor also reaches a large value of 1.58 m W·m-1·K-2at room temperature and remains non-saturated up to 400 K.Corroborating with the first-principles calculations, we find that the thermoelectric performance can be well-modulated by the carrier concentration in a wide range. This work demonstrates the Dirac semimetal Cd3As2 as a potential candidate of thermoelectric materials. 相似文献
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椭圆面积公式S=πab,其中π为圆周率,α、b分别是椭圆半短轴、半长轴的长.关于椭圆面积公式的证法有多种,文献[1]利用仿射变换与仿射不变量推导出椭圆面积公式,文献[2]通过对单位正方形的拉伸(压缩)变换前后面积关系的讨论,给出了椭圆面积公式的又一证法.文献[3]利用初等数学的方法,推导出椭圆面积的计算公式.本文利用投... 相似文献
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Coherent pulse stacking(CPS) is a new time-domain coherent addition technique that stacks several optical pulses into a single output pulse, enabling high pulse energy and high average power. A Z-domain model targeting the pulsed laser is assembled to describe the optical interference process. An algorithm, extracting the cavity phase and pulse phases from limited data, where only the pulse intensity is available, is developed to diagnose optical cavity resonators. We also implement the algorithm on the cascaded system of multiple optical cavities,achieving phase errors less than 1.0°(root mean square), which could ensure the stability of CPS. 相似文献
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Under a strong magnetic field,the quantum Hall(QH) effect can be observed in two-dimensional electronic gas systems.If the quantized Hall conductivity is acquired in a system without the need of an external magnetic field,then it will give rise to a new quantum state,the quantum anomalous Hall(QAH) state.The QAH state is a novel quantum state that is insulating in the bulk but exhibits unique conducting edge states topologically protected from backscattering and holds great potential for applications in low-power-consumption electronics.The realization of the QAH effect in real materials is of great significance.In this paper,we systematically review the theoretical proposals that have been brought forward to realize the QAH effect in various real material systems or structures,including magnetically doped topological insulators,graphene-based systems,silicene-based systems,two-dimensional organometallic frameworks,quantum wells,and functionalized Sb(111) monolayers,etc.Our paper can help our readers to quickly grasp the recent developments in this field. 相似文献
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An optical flequency comb phase-locked on an iodine frequency stabilized diode laser at 634 nm is constructed to transfer the accuracy and stability from the optical domain to the radio frequency domain. An external-cavity diode laser is frequency-stabilized on the Doppler-free absorption signals of the hyperfine transition R(80)8-4 using the third-harmonic detection technique. The instability of the ultra-stable optical oscillator is determined to be 7 ×10^-12 by a cesium atomic clock via the optical frequency comb's mass frequencv dividing technique. 相似文献
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Ultra-Stable Rubidium-Stabilized External-Cavity Diode Laser Based on the Modulation Transfer Spectroscopy Technique 下载免费PDF全文
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
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