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501.
502.
报道了连续二极管端面泵浦2 μm高重复频率Tm,Ho:YLF激光器的实验研究结果。792 nm光纤耦合激光二极管作泵浦源,泵浦液氮制冷的Tm,Ho:YLF晶体。动态运转时,平均输出功率达到4 W,相应的能量抽取效率大于85%。采用声光调Q方式,重复频率1~50 kHz可调,10 kHz时,峰值功率达到12 kW,最小脉宽为32 ns。同时,还对二极管泵浦2 μm激光器设计中的各种因素进行了分析。 相似文献
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This paper describes an experiment where the Hanle effect and the double magnetic resonance in the metastable state of an atomic transition is detected, not by a modification of the light absorbed or reemitted by the atoms, but by a modification of the refractive index of the atomic vapor. The detection is based on the deflection of the optical pumping beam by a prismatic cell containing the gas and measured with the help of a position sensitive detector. 相似文献
506.
Optical pumping and population transfer of nuclear-spin states of caesium atoms in high magnetic fields
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Nuclear-spin states of gaseous-state Cs atoms in the ground state
are optically manipulated using a Ti:sapphire laser in a magnetic
field of 1.516T, in which optical coupling of the nuclear-spin
states is achieved through hyperfine interactions between electrons
and nuclei. The steady-state population distribution in the
hyperfine Zeeman sublevels of the ground state is detected by using
a tunable diode laser. Furthermore, the state population transfer
among the hyperfine Zeeman sublevels, which results from the
collision-induced modification \delta a(\bm S \cdot \bm I) of the
hyperfine interaction of Cs in the ground state due to stochastic
collisions between Cs atoms and buffer-gas molecules, is studied at
different buffer-gas pressures. The experimental results show that
high-field optical pumping and the small change \delta a(\bm S
\cdot \bm I) of the hyperfine interaction can strongly cause the
state population transfer and spin-state interchange among the
hyperfine Zeeman sublevels. The calculated results maybe explain the
steady-state population in hyperfine Zeeman sublevels in terms of
rates of optical-pumping, electron-spin flip, nuclear spin flip, and
electron-nuclear spin flip-flop transitions among the hyperfine
Zeeman sublevels of the ground state of Cs atoms. This method may be
applied to the nuclear-spin-based solid-state quantum computation. 相似文献
507.
用Floquet方法计算电子通过含时的双δ势的透射系数.其优点在于对任何谐振势垒的强度和频率都适用.同时此方法还可以将含时的问题转化为非含时问题,进而解决含时势垒的透射问题.通过对透射系数的计算,着重考虑初相对透射系数的影响,并且详细地考察电子从任意的一个通道到任意的另一个通道的几率.结果表明初相不仅对总的透射系数有调制作用而且对通道间的传榆也有调制作用.而对于透射系数的影响程度强弱则完全取决于系统所设定的条件. 相似文献
508.
509.
ZHANG Hengli HOU Wei FENG Baohua XU Zuyan WU Baichang CHEN Chuangtian 《Chinese Journal of Lasers》2000,9(1):30-33
A diode-pumped Nd3+:YVO4 emitting at 1342 nm and 671 nm was developed. Low concentration neodymium doped Nd:YVO4 shows excellent stability at 1342 nm. With a type-Ⅱ noncritical phase-matched LBO crystal as the intracavity frequency doubler, 890 mW of 671 nm light was obtained at 11.2 W incident pumping power, the optical-optical conversion efficiency is 7.9%. 相似文献
510.
Jonathan R. Birchall Md Raduanul H. Chowdhury Panayiotis Nikolaou Yuri A. Chekmenev Anton Shcherbakov Michael J. Barlow Boyd M. Goodson Eduard Y. Chekmenev 《Molecules (Basel, Switzerland)》2022,27(4)
We present a pilot quality assurance (QA) study of a clinical-scale, automated, third-generation (GEN-3) 129Xe hyperpolarizer employing batch-mode spin-exchange optical pumping (SEOP) with high-Xe densities (50% natural abundance Xe and 50% N2 in ~2.6 atm total pressure sourced from Nova Gas Technologies) and rapid temperature ramping enabled by an aluminum heating jacket surrounding the 0.5 L SEOP cell. 129Xe hyperpolarization was performed over the course of 700 gas loading cycles of the SEOP cell, simulating long-term hyperpolarized contrast agent production in a clinical lung imaging setting. High levels of 129Xe polarization (avg. %PXe = 51.0% with standard deviation σPXe = 3.0%) were recorded with fast 129Xe polarization build-up time constants (avg. Tb = 25.1 min with standard deviation σTb = 3.1 min) across the first 500 SEOP cell refills, using moderate temperatures of 75 °C. These results demonstrate a more than 2-fold increase in build-up rate relative to previously demonstrated results in a comparable QA study on a second-generation (GEN-2) 129Xe hyperpolarizer device, with only a minor reduction in maximum achievable %PXe and with greater consistency over a larger number of SEOP cell refill processes at a similar polarization lifetime duration (avg. T1 = 82.4 min, standard deviation σT1 = 10.8 min). Additionally, the effects of varying SEOP jacket temperatures, distribution of Rb metal, and preparation and operation of the fluid path are quantified in the context of device installation, performance optimization and maintenance to consistently produce high 129Xe polarization values, build-up rates (Tb as low as 6 min) and lifetimes over the course of a typical high-throughput 129Xe polarization SEOP cell life cycle. The results presented further demonstrate the significant potential for hyperpolarized 129Xe contrast agent in imaging and bio-sensing applications on a clinical scale. 相似文献