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91.
Phase-Locked Fibre Array for Coherent Combination and Atmosphere Aberration Compensation 总被引:1,自引:0,他引:1 下载免费PDF全文
We report a fibre amplifier array that not only achieves coherent beam combination by compensation of phase noises of fibre amplifier, but also accomplishes correction of atmosphere aberration. It is of master-oscillatormultiple-amplifier (MOPA) configuration, which can be phase-locked by the multidither principle or heterodyne detection principle. First laboratory experiments of atmosphere aberration compensation of a three-element fibre amplifier array are reported. The atmosphere aberration is created by a phase screen in the experiment. The phase changes of the beam, which are introduced by the fibre amplifier and the phase screen, are both detected by the heterodyne detection method. Phase modulators are controlled to compensate for the phase in the three paths. No matter whether there is a phase screen producing atmosphere aberration or not, the dim dynamic interference fringes in the far field turn to a clear and stable pattern, and the peak intensity is maximized. It is indicated that the fibre amplifier array is phase-locked, and coherent combination of the three beams is achieved. It can be used not only to obtain high power fibre laser array but also in laser space communication. 相似文献
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94.
Sm3+掺杂稀土硼酸盐玻璃的光谱参数计算和荧光光谱分析 总被引:1,自引:1,他引:1
制备了具有高效可见荧光发射的Sm3 掺杂稀土硼酸盐(LBLB)玻璃,对玻璃的吸收和荧光光谱展开了测试与分析.根据Judd-Ofelt理论对吸收光谱进行了拟合,求得Sm3 离子的晶场调节参数Ωt=(2,4,6)分别为6.81×10-20,4.43×10-20和2.58×10-20 cm2,并进一步计算出各能级跃迁的谱线强度、自发辐射跃迁概率、辐射寿命和荧光分支比等光谱参数.紫外光激发下,Sm3 掺杂LBLB玻璃发出明亮的橙红色光.激发光谱表明,氩离子激光器是Sm3 掺杂LBLB玻璃有效的激发光源. 相似文献
95.
富硒蛹虫草中硒多糖的分离与分析 总被引:7,自引:1,他引:7
在对人工栽培的富硒蛹虫草中分离提取了水溶性硒多糖,富硒蛹虫草硒多糖的分离纯化方法是采用水提醇沉工艺,粗硒多糖得率为5.76%。系统研究了富硒蛹虫草硒多糖的浸提、纯化、分离条件,苯酚硫酸法测定了富硒蛹虫草的多糖含量为47.5%,分子荧光法测定硒多糖中含硒量为92.3 mg·kg-1。 相似文献
96.
利用水热法合成了YLiF4: Er3 , Tm3 , Yb3 , 其中Er3 和Yb3 的浓度保持固定不变, 分别为1 mol%和1.5 mol%, Tm3 浓度变化范围是2 mol%~8 mol%. 在这种共掺杂体系中, 同时观察到了Er3 , Tm3 和Yb3 的吸收, 且Tm3 的吸收随着其浓度的增强而增强. 在980 nm光的激发下, 当Tm3 浓度很小时, 这种材料的上转换发光为白光. 其中蓝光主要来源于Tm3 的激发态1G4到基态3H6的跃迁, 绿光来源于Er3 的4S3/2和2H11/2到基态4I15/2的跃迁, 红光既来源于Tm3 的1G4→3F4的跃迁, 也来源于Er3 的4F9/2→4I15/2的跃迁. 并且这种上转换发光强度随着Tm3 浓度的增强而降低, 但对应不同能级跃迁的发光强度降低的幅度不同, 这是因为Er3 和Tm3 之间的相互作用. 相似文献
97.
XIA Li-Li LI Yuan-Cheng HOU Qi-Bao WANG Jing 《理论物理通讯》2006,46(4):683-686
Based on the total time derivative along the trajectory of the system, the unified symmetry of nonholonomic mechanical system with non-Chetaev's type constraints is studied. The definition and criterion of the unified symmetry of nonholonomic mechanical systems with non-Ohetaev's type constraints are given. A new conserved quantity, as well as the Noether conserved quantity and the Hojman conserved quantity, deduced from the unified symmetry, is obtained. Two examples are given to illustrate the application of the results. 相似文献
98.
A Q-Swicthed All-Solid-State Single-Longitudinal-Mode Laser with Adjustable Pulse-Width and High Repetition Rate 下载免费PDF全文
A single-longitudinal-mode (SLM) laser-diode pumped Nd: YAG laser with adjustable pulse width is developed by using the techniques of pre-lasing and changing polarization of birefingent crystal The Q-switching voltage is triggered by the peak of the pre-lasing pulse to achieve the higher stability of output pulse energy. The output energy of more than I mJ is obtained with output energy stability of 3% (rms) at lOO Hz. The pulsewidth can be adjusted from 30ns to 300ns by changing the Q-switching voltage. The probability of putting out single-longitudinal-mode pulses is almost 100%. The laser can be run over four hours continually without mode hopping. 相似文献
99.
In the presence of an applied static and uniform magnetic field, a cylindrical Kadomtsev-Petviashivili equation is derived for a relativistic electromagnetic solitary wave propagating in collisionless plasma consisting electrons, positrons, and ions in the case of weak relativistic limit. This equation is solved in a stationary frame to obtain explicit expression for the velocity, amplitude and width of solitons. The amplitude of the solitary wave has a maximum value at a critical αc of the ratio of the ion equilibrium density to the electron one, and it increases as the applied magnetic field becomes larger. 相似文献
100.
Generation of 2.1 W Continuous Wave Blue Light by Intracavity Doubling of a Diode-End-Pumped Nd:YAG Laser in a 30 mm LBO 总被引:2,自引:0,他引:2 下载免费PDF全文
A folded four-mirror cavity with a composite Nd:YAG rod is optimized to obtain high efficient cw 473nm blue output. The laser could operate stably in the region of the thermal-lens focal length from 20mm to 70mm. LBO is used for intracavity frequency doubling of the 946nm transition of Nd:YAG and the optimum LBO length is investigated. A maximum output power of 2.1 Win the blue spectral range at 473nm is achieved with 30-mm-long LBO, corresponding to an optical conversion efficiency of 9.1%. 相似文献