基于单晶体的可调谐参量超荧光的产生

研究了一种基于单晶体的可调谐超荧光产生机理，在一个偏硼酸钡(BBO)晶体中实现了飞秒脉冲倍频过程和光参量产生过程.实验中采用kHz高功率钛宝石激光系统输出的飞秒脉冲光倍频后的蓝光作为抽运光，获得了可调谐范围为480—530 nm参量超荧光光谱输出.理论上分析了这种超荧光产生机理，并利用放大传递函数模拟出参量超荧光环的产生过程.结果表明，在一个BBO晶体中，当抽运光源输出光入射晶体角度同时满足倍频相位匹配角和非共线光参量产生相位匹配角时可产生参量超荧光环，通过微调相位匹配角可控制参量超荧光光谱调谐输出.该理论和实验研究为控制参量超荧光和量子纠缠态的产生提供了理论依据，对于量子成像和量子通讯等领域的发展具有重要意义.     

多级碱金属蒸气激光放大器的输出特性

在全面分析碱金属蒸气激光放大器的激光动力学与流体动力学过程的基础上,结合热效应、饱和放大效应、放大自发辐射、高能级激发与电离的影响,建立了一个相对完善的物理模型来模拟流动散热条件下半导体抽运碱金属蒸气激光放大器的输出特性。计算模拟了纵向和横向两种不同流动方式下,气体流速对输出功率的影响,比较分析了高抽运功率密度下各能级粒子数密度的变化趋势,最后模拟了各级放大器的功率分配比对提高级联放大器输出效率的作用。结果表明:在相同工作温度条件下,多个等长蒸气池和均等抽运光功率分配能让高级数放大器获得比低级数放大器更高的放大倍数。所提模型有助于高功率碱金属蒸气激光放大器的参量选择和优化设计。     

用遗传算法优化铜激光放电电路的LC参量

将遗传算法应用于铜蒸气激光(CVLs)计算机动力学模型,以最大输出激光功率为目标函数,优化了CVLs放电电路的LC参量.优化后,储能电容为726nF(实验选8nF,储能电容与峰化电容之比为108(实验选3∶1),两等效电感之比为4∶1(实验选2∶1).优化后激光输出功率增加了15%. 关键词：     

掺氢与激励电路对钡蒸气激光输出特性的影响

对用Blumlein电路放电激励的钡蒸气激光在掺氢和不掺氢时的输出特性进行了实验研究 .结果表明 ,用掺氢1 5 %的氖气作缓冲气体能使激光功率增加近 2倍 .在此基础上 ,进一步比较了相互作用电路与Blumlein电路时钡蒸气激光的输出特性 ,发现相互作用电路能显著提高钡蒸气激光的输出功率和效率 ,获得了 3W最大功率和 0 4 %效率的 1 5 μm波长激光输出 .测量并分析了各工作参量与激光功率之间的关系 ,定性解释了掺氢与相互作用电路的作用机理     

掺氢与激励电路对钡蒸气激光输出特性的影响

对用Blumlein电路放电激励的钡蒸气激光在掺氢和不掺氢时的输出特性进行了实验研究.结果表明，用掺氢1.5%的氖气作缓冲气体能使激光功率增加近2倍.在此基础上，进一步比较了相互作用电路与Blumlein电路时钡蒸气激光的输出特性，发现相互作用电路能显著提高钡蒸气激光的输出功率和效率，获得了3W最大功率和0.4%效率的1.5μm波长激光输出.测量并分析了各工作参量与激光功率之间的关系，定性解释了掺氢与相互作用电路的作用机理 . 关键词： Blumlein电路 相互作用电路 掺氢 钡蒸气激光     

非线性附加耦合腔产生超短激光脉冲

系统地研究了用带有非线性倍频晶体的附加耦合腔来压窄激光光脉冲的动力学作用过程，首次给出了该锁模激光系统在瞬态平衡时输出脉宽的具体表达式，实验测量结果与理论计算值相比吻合得很好；最后，文中还报道了有关实验参量与该锁模激光系统输出特性的关系曲线。     

纵向脉冲放电的Ne-CuBr紫外激光参量的数值研究

建立了一个描述纵向脉冲放电的Ne-CuBr紫外激光的动力学模型，数值计算了实验中主要参量对激光性能的影响.给出了激光输出特性随缓冲气压、工作温度和激光管口径之间的变化关系，定量解释了已有的实验结果，为进一步提高激光输出性能提供了依据. 关键词： Ne-CuBr紫外激光 脉冲放电 参量研究     

大口径铜蒸气激光器的动力学分析

通过建立调整大口径铜蒸气激光器的动力学模拟过程中的有关动力学参数,得到一适用于不同输出功率的大口径铜蒸气激光器动力学模型.在此基础上对大口径铜蒸气激光器的径向动力学参量进行了计算,包括激励电场和亚稳态铜粒子密度等动力学参量的径向分布.给出了大口径铜蒸气激光器的径向电子温度及发光强度分布.尔后得到在不同充电电压及缓冲气压条件下铜蒸气激光器的输出功率,此程序对Φ=65cm的大口径铜蒸气激光器的计算结果与实验符合得相当好. 关键词：     

LD泵浦碱金属蒸气激光器中弛豫与猝灭的产热分析

介绍了一个结合速率方程、泵浦光功率和输出激光功率的轴向微分方程以及温度的径向微分方程的碱金属蒸气激光器的物理模型.在充分考虑泵浦光和激光光斑半径的轴向分布以及它们光强的径向分布的基础上,模型再现了实验测量得到的有激光输出与无激光输出情况下蒸气池内的峰值温度,对应50 W、220 W和370 W的泵浦光,在有激光输出情况下的峰值温度分别为346℃、480℃和696℃;在没有激光输出条件下的峰值温度分别为321℃、414℃和609℃,总体温度曲线与实验一致.模型计算所得的猝灭的产热量在有激光输出时占总产热量的85%左右,在无激光输出时则占95%以上,这是因为猝灭涉及的跃迁能级的能级差较大,且所占热源区域较宽,能在更大的范围内产生热量,因此猝灭在温度计算中非常重要,不可忽略.     

LD端面抽运Nd:YLF/KTA连续光参量振荡激光

采用非临界相位匹配切割,尺寸5mm×5mm×20mm的KTA作为非线性光学晶体,进行了基于半导体激光端面抽运Nd:YLF/KTA的内腔式连续光学参量振荡激光研究,获得了中红外3.5μm波段的连续激光输出。为了提高连续光参量振荡腔内信号光的功率密度,降低激光输出阈值,采用对信号光高反射的单谐振腔结构进行激光实验。在8.35W的抽运功率下,分别获得了335mW和110mW的3440nm和1505nm的激光输出,对应的总转换效率达到了5.6%。该实验研究表明半导体激光端面抽运的内腔式KTA连续光学参量振荡也能获得高效的中红外激光输出。     

Modeling of a diode transverse-pumped cesium vapor laser

A physical model is established to demonstrate the mechanism and the kinetic process of a diode transverse-pumped cesium vapor laser. The distribution of pump laser power is described, and the effects of parameters such as the temperature, the cell length and the output coupler reflectivity on the output performance of a cesium vapor laser are simulated and analyzed. The simulation results agree well with the experiment data which shows the validity of this model. A set of optimization parameters is achieved for improving the output characteristics of a diode transverse-pumped Cs vapor laser.     

离子推力器工作性能参数控制模型

为了研究离子推力器工作参数对输出特性的影响,通过离子推力器工作性能参数的理论计算公式,建立起离子推力器输入参数与输出参数的Simulink控制模型,根据模型分别对我国研制的30 cm口径以及20 cm口径离子推力器的工作输出参数进行了理论计算,并通过推力测量试验对理论值进行了比对和分析。比对结果表明:在推力理论计算过程中引入二价Xe离子比率和束流密度分布推力修正,以及推力均方误差修正后,推力理论值与实测值符合性较好,计算误差小于1 mN,证明了推力修正方法的合理性。     

Implication of two-coupled tri-stable stochastic resonance in weak signal detection

Stochastic resonance(SR) has been proved to be an effective approach to extract weak signals overwhelmed in noise.However, the detection effect of current SR models is still unsatisfactory. Here, a coupled tri-stable stochastic resonance(CTSSR) model is proposed to further increase the output signal-to-noise ratio(SNR) and improve the detection effect of SR. The effects of parameters a, b, c, and r in the proposed resonance system on the SNR are studied, by which we determine a set of parameters that is relatively optimal to implement a comparison with other classical SR models.Numerical experiment results indicate that this proposed model performs better in weak signal detection applications than the classical ones with merits of higher output SNR and better anti-noise capability.     

The influences of amplified spontaneous emission,crystal temperature and round-trip loss on scaling of CW thin-disk laser

In this paper, a model is built to explore how the parameters (amplified spontaneous emission (ASE), temperature and round-trip loss) influence the output power in a thin-disk laser. It is found that optical efficiency of the disk laser is reduced with the increase of ASE, temperature or round-trip loss. The parameters are optimized to maximize the output power based on our model. We find that it is necessary to balance the need to lower the temperature with the need to control ASE during the optimization process. But the balance becomes more difficult to achieve with the increase of round-trip loss. We conclude that output power of more than 2.6 MW with a single disk can be achieved, but the necessary disk size (more than 0.5 m) is far beyond the actual technical limits. But it is possible to achieve output power of over a hundred kilowatts using a 10 cm disk in the near future.     

A CAD oriented quasi-analytical large-signal drain current model for 4H-SiC MESFETs

This paper reports that a 4H-SiC MESFET (Metal Semiconductor Field Effect Transistor) large signal drain current model based on physical expressions has been developed to be used in CAD tools. The form of drain current model is based on semi-empirical MESFET model, and all parameters in this model are determined by physical parameters of 4H-SiC MESFET. The verification of the present model embedded in CAD tools is made, which shows a good agreement with measured data of large signal DC I-V characteristics, PAE (power added efficiency), output power and gain.     

锥形太赫兹量子级联激光器输出功率与光束特性研究

针对锥形太赫兹量子级联激光器, 利用有限差分波束传播法和速率方程法, 建立了准三维的太赫兹有源器件仿真模型, 能够对具有轴向非线性波导结构的激光器进行模拟. 利用此模型, 研究了锥角大小对激光器输出光功率及光束质量的影响. 仿真结果表明, 考虑到器件之间的光耦合效率, 为了达到最大的有效输出光功率, 锥形太赫兹量子级联激光器的锥角存在一个最优值.     

腔镜形变对圆筒组合型CO_2激光器模式的影响

针对具有锁相结构的圆筒组合型CO2激光器,分析了其注入锁定的原理,利用等价条形腔理论,建立了分析其输出基模的数学模型。利用该模型,研究了不同形变量对圆筒形腔输出基模的影响。结果表明,为了获得与注入光束模式类似的光场分布,复曲面镜与圆筒形谐振腔中平面镜镜面中心的形变量应控制在0.07倍波长以内。同时,分析在不同腔镜参数情况下腔镜形变对输出模式造成的影响,其结果有利于进一步优化谐振腔的参数设计。     

材料参数对光伏型探测器光电特性的影响

基于改进的漂移-扩散模型研究了光伏型光电探测器的材料参数对其光电特性的影响.计算结果表明载流子迁移率、材料组分、掺杂密度对探测器输出特性的影响大;载流子寿命越长、迁移率越大、杂质密度越小,则探测器输出信号越大,但各材料参数与探测器输出信号间并不构成线性关系;当入射光波长一定时材料组分不同探测器输出信号大小不同.     

Modeling and optimization of stable gain-switched Tm-doped fiber lasers

A numerical model that describes the operation behaviors and output characteristics of stable gain-switched Tm-doped fiber (Tm:fiber) lasers resonantly pumped at 1.56 mm is presented in this paper. Effects of some important laser parameters, such as repetition rates, pump power levels, transmission of the laser output coupler, fiber core sizes, fiber lengths, Tm concentrations, etc., on laser output were investigated. The model and simulating results were verified by preliminary experiments and good agreements have been achieved, suggesting that the model are useful for design and optimization of stable gain-switched Tm:fiber lasers at 2 mm wavelength region.     

Design and Optimization of the Electromagnetic Actuator in Active-Passive Hybrid Vibration Isolator

The design and optimization of actuators are difficult and critical for the active-passive hybrid vibration control system. In this paper, an electromagnetic actuator model is established based on Ohm’s Law for magnetic circuit considering the leakage flux. The 600N electromagnetic actuators are designed and optimized based on ANSYS simulation according to the engineering request. Its transient characteristics are studied. The effects of different structural parameters on its output force are analyzed. The experimental results show that the structure parameters and output force characteristics of the designed electromagnetic actuators satisfy the practical requirement.