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21.
Coherent beam combination of adaptive fiber laser array with tilt-tip and phase-locking control
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We present an experimental study on tilt-tip(TT) and phase-locking(PL) control in a coherent beam combination(CBC) system of adaptive fiber laser array.The TT control is performed using the adaptive fiber-optics collimator(AFOC),and the PL control is realized by the phase modulator(PM).Cascaded and simultaneous controls of TT and PL using stochastic parallel gradient descent(SPGD) algorithm are investigated in this paper.Two-fiber-laser-,four-fiber-laser-,and six-fiber-laser-arrays are employed to study the TT and PL control.In the cascaded control system,only one high-speed CMOS camera is used to collect beam data and a computer is used as the controller.In a simultaneous control system one high-speed CMOS camera and one photonic detector(PD) are employed,and a computer and a control circuit based on field programmable gate array(FPGA) are used as the controllers.Experimental results reveal that both cascaded and simultaneous controls of TT using AFOC and PL using PM in fiber laser array are feasible and effective.Cascaded control is more effective in static control situation and simultaneous control can be applied to the dynamic control system directly.The control signals of simultaneous PL and TT disturb each other obviously and TT and PL control may compete with each other,so the control effect is limited. 相似文献
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Efficient Phase Locking of Fiber Amplifiers Using a Low-Cost and High-Damage-Threshold Phase Control System
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We propose a low-cost and high-damage-threshold phase control system that employs a piezoelectric ceramic transducer modulator controlled by a stochastic parallel gradient descent algorithm. Efficient phase locking of two fiber amplifiers is demonstrated. Experimental results show that energy encircled in the target pinhole is increased by a factor of 1.76 and the visibility of the fringe pattern is as high as 90% when the system is in close-loop. The phase control system has potential in phase locking of large-number and high-power fiber laser endeavors. 相似文献
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Passive Coherent Beam Combining Four Channels of Nanosecond Pulsed Laser Using All-Fiber Feedback Loop
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We present an all-fber configuration of passive beam combining using an all-fber feedback loop and demonstrate passive coherent combining of a four-channel nanosecond pulsed laser. The output power, pulse characteristics, polarization extinction ratio and far field laser intensities of the combined output laser are investigated. The experimental results validate that passive phasing using an all-fiber feedback loop provides a simple while robust method for coherent beam combining of pulsed lasers. If replacing the fiber coupler used into a high power tapered fused bundle fiber combiner, this scheme ispromising to scale the output power up to the kW level. 相似文献
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如图所示,一半径为a的非常小的圆环,在起始时刻与一半径为 b (b》a)的很大的圆环共面且同心.今在大环中通以不变的电流I,而小环则以ω围绕着一条直径作匀角速转动.设小环的电阻为R,试求: (1)小环中的感生电流; (2)使小环转动时须作用在其上的力矩; (3)大环中的感生电动势. 以上是近几年研究生入学试题中多次采用的问题.但几乎所有的参考书[1][2][3]对第(3)问都给出了错误的解答. 事实上,我们容易求得: (1) 小环中的感生电流为o)为使ony转动而加的转动力短为对第O)问,书上一般是这样解的:因为 I在,Jny所在处产生的磁场为生为Z方向的单位矢… 相似文献
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