LD端面泵浦的1.57μm内腔式OPO

1.57 μm波长激光为人眼安全波长激光。将KTP晶体置于一个由LD端面泵浦、声光调Q的Nd:YVO4晶体双凹谐振腔内,利用KTP表面镀膜建立了内腔式OPO,实现了重复率在5～40 kHz范围内1.57 μm脉冲激光的稳定输出。实验结果表明,激光的阈值将随声光调Q器重复率的增加而升高,重复率为5 kHz时得到最低阈值1.52 W。重复率为15 kHz、泵浦功率为3.7 W时,输出光平均功率为305 mW,脉冲宽度50 ns,峰值功率400 W。     

LD泵浦的声光调Q 1.34 μm Nd:GdVO4激光器

对于连续泵浦的内腔式倍频、参量振荡等非线性激光器件,常需要准连续运转来提高腔内的峰值功率,声光调Q是目前获得准连续运转激光器的重要途径。在LD端泵a向生长Nd:GdVO4晶体1.34 μm静态激光的基础上,利用声光调Q对1.34 μm的动态激光进行了实验研究。当声光调Q器件重复率为5 kHz时,获得的最短脉宽为170 ns,此时的单脉冲能量为44.8 μJ,峰值功率为256 W。实验表明,1.34 μm平均功率随声光调Q的重复率增加而增大,脉冲宽度随重复率的减小而变短,因而低重复率下可得到更高的峰值输出功率。     

重复率固体激光器电源

重复率固体激光器在焊接、打孔、切割、显示、测距及军事技术、科学实验中获得越来越多的应用。在重复率激光器里,通常用氙闪光灯激发,从而涉及到重复率电源的设计和试制问题。本文简要介绍重复率固体激光器的电源设计的某些要点以及试制过程中的点滴经验,并提供一个重复率固体激光器电源的实际方案。     

激励电路参数对TEA CO2激光器寿命的影响

本文利用激励电路参数最佳化法,使高重复率小型TEA CO_2激光器,在40Hz重复率下工作时,连续工作寿命达到10~5脉冲。     

重复率YAG激光脉冲同步泵浦染料激光器

用热稳定腔主被动锁模重复率脉冲YAG激光器的倍频光,同步泵浦R6G染料激光器。获得平均功率14mW,单脉冲峰值功率大于5MW,单脉冲宽度28ps,脉冲列重复率为20pps。可调范围为555.0至586.5nm,谱线宽度约0.1nm,最窄谱宽为0.04nm,转换效率11％的可调谐激光。     

高重复率窄脉宽Nd∶YVO_4板条激光器

部分端面抽运的混合腔板条激光器是一种新型的全固态激光器,采用这种结构,实现了高重复率调Q运转。在脉冲抽运情况下,1kHz运转时,得到脉宽4.6ns,单脉冲能量4.5mJ的激光输出。在连续抽运调Q输出情况下,5kHz高重复率运转时,获得了脉宽6ns,单脉冲能量3.1mJ的脉冲序列输出,平均功率超过15W;当重复率高达25kHz时,得到脉宽9.5ns,单脉冲能量1.2mJ的激光输出,平均功率达30W。实验结果表明,输出水平还有很大的提升空间。     

激光二极管连续抽运电光调Q Nd:YVO4激光器

报道了全固态激光器连续抽运高重复率电光调Q的实验和理论分析结果。用LGS（La3Ga5SiO14）晶体作电光调Q元件，在激光二极管（LD）端面抽运Nd：YVO4激光器中实现了较高重复率的电光调Q输出。实验中在10^4Hz重复率下，抽运功率为28w时，平均功率超过5W，脉冲宽度为7ns，峰值功率为70kW，并对不同重复率时的脉冲输出进行了比较，在低重复率下，脉宽〈6．5ns，峰值功率超过100kW。在理论上，通过对连续抽运时的电光调Q速率方程进行修正，并考虑放大自发辐射（ASE）的影响，对调Q激光器的储能过程和脉冲输出特性进行了模拟，所得结果和实验数据能够很好地吻合。最后，利用LasCad软件对晶体的热效应进行了模拟，并利用临界稳定腔方法对热焦距进行了测量，测量和模拟结果基本一致。     

1.5μm高重复率超短光脉冲的产生

利用增益开关技术产生了1.5μm波长的高重复率超短光脉冲,其重复率从2.2GHz到3.5GHz,脉宽小于50ps。     

火花泵浦染料激光器

把一个短的小直径火花源和染料盒并排装在球面腔内,电输入小到5毫焦耳就可获得重复率高达2000次/秒的激射。美国联合飞机公司研究实验室的费拉尔（C. M. Ferrar)报导,在乙醇溶液里使用若丹明6G可能达到低阈值。乙醇的热光特性较差,要用水溶液来获得高重复率;在重复率为2000次/秒时,输入阈值功率增加到0.1焦耳。以使装在激光共振器上的一个未涂膜的简单玻璃标准具倾斜的方法来进行激光调谐。     

自由电子激光器获得创记录输出

美国能源部托马斯·杰菲森国家加速器装置的科学家已使该装置的自由电子激光器在 3.1μm处达到 1.72 k W的世界记录 ,将其推入可供许多实际应用的阶段。该激光器发射近衍射极限光束 ,以 18,37或 75 MHz的重复率产生约 1ps的脉冲。该装置 1998年 6月首次出光 ,当时的输出功率为 15 5 W,高于此类自由电子激光器输出的 10倍。此激光器由一超导射频直线加速器供能 ,后者又由一激光激励的电子源馈入 ;总长度约 5 0 m。电子源由将光电阴极蒸发出电子的倍频 Nd∶ YL F激光器组成 ,其重复率决定了自由电子激光的重复率。据该项目经理Fred Dylla…     

Pulse velocity in a resonant absorber

Experiments are reported that measure the pulse velocity of a mode-locked 6328-Å He-Ne laser pulse in a resonant absorber as a function of the pulse intensity. At low intensities, pulse velocities greater than the velocity of light in the passive medium are observed. These results are compared with a simple theory based on the saturation of the dispersion associated with the absorption. At higher intensities where the pulse approaches a 2π pulse, pulse delays (that is pulse velocities less than the velocity of light in the passive medium) are observed.     

光子晶体光纤中抽运脉冲参量对脉冲俘获的影响

用数值方法研究了超短脉冲在光子晶体光纤中传输时的俘获特性,得到了抽运脉冲参量对脉冲俘获率的影响规律.结果表明,对同一脉宽的抽运脉冲,随着抽运脉冲与信号脉冲的中心时延增大,俘获率的变化有一起伏过程,存在最大俘获率,而信号脉冲蓝移和抽运脉冲红移范围与时延无关.而随着脉宽增加,对应的最大俘获率和相应的时延都减小,信号脉冲的蓝移和抽运脉冲的红移都加大.因此,通过适当调控抽运脉冲的有关参量,可获得最佳的脉冲俘获率,进而达到提高光开关效能的目的.     

Pulse energy gain saturation in subpico- and picosecond pulseamplification by a traveling-wave semiconductor laser amplifier

Optical pulses with durations ranging from 0.49 to 21 ps are amplified by a traveling-wave semiconductor laser amplifier. The pulse energy gain is determined by pulse energy only. The dependence of pulse energy gain on output pulse energy does not change in the pulse duration range. The saturation characteristics are successfully explained by a four-level system model     

Different pulse shapes to obtain small fiber selective activation by anodal blocking--a simulation study

The aim of this study was to investigate whether it is possible to reduce a charge per pulse, which is needed for selective nerve stimulation. Simulation is performed using a two-part simulation model: a volume conductor model to calculate the electrical potential distribution inside a tripolar cuff electrode and a human fiber model to simulate the fiber response to simulation. Selective stimulation is obtained by anodal block. To obtain anodal block of large fibers, long square pulses (> 350 micros) with a relatively high currents (1-2.5 mA) are usually required. These pulses might not be safe for a long-term application because of a high charge per pulse. In this study, several pulse shapes are proposed that have less charge per pulse compared with the conventional square pulse and would therefore be safer in a chronic application. Compared with the conventional square pulse, it was possible to reduce the charge with all proposed pulse shapes, but the best results are obtained with a combination of a square depolarizing pulse and a blocking pulse. The charge per pulse was up to 32% less with that pulse shape than with a square pulse. Using a hyperpolarizing anodal prepulse preceding a square pulse, it was not possible to block nerve fibers in a whole nerve bundle and to obtain reduction of a charge per phase. Reduction of the charge could be achieved only with spatially selective blocking. The charge per phase was larger for the combination of a hyperpolarizing anodal prepulse and a two-step pulse than for the two-step pulse alone.     

强激光打靶产生电磁脉冲特性与传导防护研究

为了降低电磁脉冲的场强大小,加强强激光打靶产生电磁脉冲的传导防护性能,提出了强激光打靶产生电磁脉冲特性与传导防护研究.由于强激光打靶产生电磁脉冲对各种电子设备和电气设备都会造成一定威胁,采用双指数函数,分析了强激光打靶产生电磁脉冲的时域波形频谱,完成了强激光打靶产生电磁脉冲的特性研究;为了消除强激光打靶产生的电磁脉冲波...     

Peak pulse voltage measurement

Several methods are presently being used for the measurement of pulse voltage. Oscilloscopes are particularly useful because they provide information concerning the shape of the pulse, besides a measure of the peak voltage. In addition to the oscilloscope, several peak voltmeter circuits are mentioned. These include pulse stretching, sampling, and the slideback method. A standard pulse generator is described which provides a calibrated pulse voltage suitable for voltmeter calibration and other uses.     

Propagation Characteristics of Infrared Pulse Waves through Windblown Sand and Dust Atmosphere

The physics characteristics of the windblown sand and dust atmosphere at the sand bench of Yellow River in China are discussed. The pulse distortion and time delay of infrared nanosecond pulse propagating through the atmosphere having sand and dust particles are investigated at 1.06 and 3.8 μm, respectively. It is shown that the delay of 10 ns laser pulse propagating through 5 km windblown sand and dust atmosphere are over 1 ns and 10 ns at 1.06 and 3.8 μm, respectively. The pulse spread increases slightly with wavelength increase. The pulse spread of a 10 ns laser pulse is over 40 ns at 3.8 μm. The pulse delay and spread increase rapidly with the sand particle density increasing in atmosphere. The narrower the pulse width is, the more the pulse distortion is. Hence, at infrared band, for a laser pulse propagating in sand and dust atmosphere, the pulse delay and spread are quite severe and need be taken into account for a narrower pulse laser system.     

Efficient infrared-terahertz pulse conversion in waveguide semiconductor structures

It is shown that the use of a waveguide semiconductor structure provides a means for substantially increasing the degree of conversion of a high-power infrared pulse to a terahertz pulse by optical rectification of the infrared pulse in a medium with a quadratic nonlinearity of the permittivity. Using the example of the C/GaAs/C waveguide heterostructure, the optimal parameters of both the structure as such and the infrared pulse are determined and the duration and shape of the output terahertz pulse are calculated.     

10ns～500ns宽度连续可调的快速光脉冲发生器

脉宽可调的脉冲发生器常用于精密检测。本文阐述了一种运用叠加原理设计的脉冲宽度从10ns到500ns连续可调的快速光脉冲发生器。在驱动电路中应用了脉冲叠加原理。     

大功率脉冲调制管的设计

叙述了脉冲调制器对调制管的要求,研究了阳栅之间空间电荷效应对调制管阳极特性的影响,提出了满足调制器要求的脉冲调制管的新的设计思想。