螺旋型波荡器辐射特性及光束线前置镜热载分布

对合肥国家同步辐射实验室(NSRL)引进、装备的螺旋型电磁波荡器进行了改造和性能研究,该螺旋型电磁波荡器被插入电子储存环的直线段,来产生高通量圆偏振相干光,提供一条真空紫外光束线,用于燃烧科学研究.基于NSRL改造后的光源参数,分析其同步辐射偏振特性,计算了该波荡器辐射出的总功率和功率密度分布,以及受其直接辐照的光束线...     

Simultaneous time and wavelength resolved spectroscopy under two-colour near infrared and terahertz excitation

Time and wavelength resolved spectroscopy requires optical sources emitting very short pulses and a fast detection mechanism capable of measuring the evolution of the output spectrum as a function of time. We use table-top Ti:sapphire lasers and a free-electron laser (FEL) emitting ps pulses as excitation sources and a streak camera coupled to a spectrometer for detection. One of the major aspects of this setup is the synchronization of pulses from the two lasers which we describe in detail. Optical properties of the FEL pulses are studied by autocorrelation and electro-optic sampling measurements. We discuss the advantages of using this setup to perform photoluminescence quenching in semiconductor quantum wells and quantum dots. Carrier redistribution due to pulsed excitation in these heterostructures can be investigated directly. Sideband generation in quantum wells is also studied where the intense FEL pulses facilitate the detection of the otherwise weak nonlinear effect.     

A two-step system for compression of microwave pulses in series-coupled resonators

A system for resonance compression of microwave pulses consists of two resonators connected in series: the first is a high-Q oversized resonator and the second is a single-mode cylindrical resonator. The time dependences of the field strength in the resonators during their excitation and the energy transfer at different values of the transfer coefficient have been determined for the 10-cm wavelength region. The results of experimental studies are presented. The output pulses are 3 ns in length and have a maximum pulse power of 1.2 GW.     

应用CWDM实现FBG传感解调的研究

本文利用粗波分复用器（CWDM）的传输特性与波长的关系，提出了一种FBG传感解调方法并建立了实验系统。通过理论分析计算，得出系统的输入／输出之间的关系，并进行了实验验证。系统的波长解调范围为4nm左右，在没有进行光功率补偿的情况下，根据实验数据的分析计算，方差最差的情况下σmax=4pm。本系统在对分辨率要求不高的工程实际中的动态解调有着广泛的应用前景。     

Influence of the cavity parameters on the output intensity in incoherent broadband cavity-enhanced absorption spectroscopy

The incoherent broadband cavity-enhanced absorption spectroscopy is a technique in measuring small absorptions over a broad wavelength range. The setup consists of a conventional absorption spectrometer using an incoherent lamp and a charge coupled device detector, as well as a linear optical cavity placed around the absorbing sample, which enhances the effective path length through the sample. In this work the consequences of cavity length, mirror curvature, reflectivity, different light injection geometries, and spot size of the light source on the output intensity are studied and the implications to the signal-to-noise ratio of the absorption measurement are discussed. The symmetric confocal resonator configuration is identified as a special case with optimum imaging characteristics but with higher requirements for mechanical stability. Larger spot sizes of the light source were found to be favorable in order to reduce the negative effects of aberrations on the intensity.     

体布拉格光栅外腔倍频半导体激光器研究

为提高绿光激光器的输出特性,设计了一种体布拉格光栅外腔倍频半导体激光器。采用反射型体布拉格光栅作为反馈元件构成外腔半导体激光器,并使用三硼酸锂晶体进行倍频,研究了基频光的光束及光谱特性对倍频光的光束及光谱特性的影响。实验结果表明,使用体布拉格光栅进行外腔锁波时,所得到的倍频光同样能实现窄带宽输出,同时倍频光的远场分布与基频光的远场分布一致。使用衍射效率为10%的体布拉格光栅作为外腔输出镜,可将半导体激光器的输出波长稳定锁定在1 064 nm,所得到的倍频光波长稳定在532 nm附近,光谱线宽压缩至0.4 nm左右,输出功率可达73 mW。     

VIBRATION MEASUREMENT OF DOUBLE-ENDED TUNING FORKS RESONATOR

To enhance the coherence and reliability of the double-ended tuning fork (DETF) resonator, a measurement system of resonator vibration is presented to check its dynamic characteristics. Laser Doppler techniques are utilized and the relation between DETF vibration velocity and output current of photodetector is obtained. Resonator vibration equation is also analyzed and its driving power only depends on the direct current bias voltage and the amplitude of alternative voltage. Furthermore, a special resonator driving control circuit based on measurement is designed. The amplitude and frequency of circuit is controlled by a computer so that highly stable and strong driving signal can be output. Experiments on driving and measuring double-ended tuning fork have been done. The frequency of driving signal is 8 kHz and the peak-to-peak value of driving voltage is 140 V. Experimental results indicate resonator can be drived stably by driving control circuit and dynamic characteristics of DETF may be measured in real time.     

双芯光纤马赫-曾德尔干涉仪的温度特性

对适用于温度传感的双芯光纤马赫-曾德尔干涉仪进行了研究,并通过将一根单模双芯光纤熔接在两根单模光纤之间,制得了双芯光纤马赫-曾德尔干涉仪型梳状滤波器.用干涉原理分别分析了该器件传输谱的自由空间谱宽与波长、双芯光纤的长度和两纤芯间的有效折射率差的关系,实验检测了它的温度特性.结果显示,随着温度的升高,该器件的传输谱发生红...     

Laser beam quality and pointing measurement with an optical resonator

We present a compact diagnostic breadboard that is based on an optical ring resonator for measuring beam quality and pointing of single-frequency continuous wave lasers at a wavelength of 1064 nm. To determine the beam quality of the coherent test beam, this optical resonator is used to perform a mode decomposition into Hermite-Gaussian modes. For our laser system, a power fraction in the fundamental Gaussian mode of 97.2%+/-0.2% was measured. Residual misalignment and mis-mode-matching to the resonator as well as the astigmatism and/or ellipticity of the test beam have been determined. Numerical simulations showed that measurements of the M(2) factor and transversal intensity distribution are not suitable for determining this power fraction. To measure the beam pointing, the fundamental mode of the optical resonator was used as a stable reference. The pointing of the test beam was measured with the differential wave front sensing technique up to Fourier frequencies of 1 kHz with a sensitivity to relative pointing of /epsilon/=1x10(-6)/sqrt[Hz]. Pointing measurements with an alternative method were performed and showed good agreement.     

康复机器人准零刚度隔振特性分析与实验

为了解决康复机器人低频振动对人体的影响问题,提出并设计一种具有准零刚度特性的新型被动隔振机构,它由两个对称的具有负刚度特性的拉伸弹簧并联一个线性正刚度弹簧实现。首先,通过静力学特性,建立此隔振机构的力-位移和刚度-位移关系式,得出机构在静态平衡位置处具有准零刚度特性的参数条件;其次,通过动力学特性,建立其分别在简谐力和简谐位移激励下的非线性微分动力学方程,采用谐波平衡法分析机构参数与激励对系统力传递率、位移传递率的影响;最后,通过实验验证在有、无负刚度情况下,输入与输出的曲线。结果表明,在有负刚度机构的情况下,隔振系统具有一定范围的准零刚度特性,且低频隔振性能较好,达到了高静态、低动态刚度的效果。本研究对机器人低频隔振具有创新性和指导意义。     

三相三线制SPWM逆变器死区效应分析

针对死区时间的加入所带来的死区效应(如对输出电压基波和低次谐波含量的影响),建立了定量计算的数学模型,详细分析了不同条件下,死区效应与死区时间、调制系数、开关频率和功率因数角之间的关系。在Matlab上对其进行了Simulink仿真,在一台3 kW三相三线制逆变器上进行了实验。理论分析结果表明,死区时间的引入会降低输出电压基波幅值和增大低次谐波的含量。理论曲线和仿真、实验数据拟合曲线基本吻合,验证了数学模型的正确性。该分析对SPWM逆变器的设计具有一定的参考意义。     

基于透射式非稳腔的单纵模TEA CO_2激光器

为了获得TEA CO_2激光器高质量的单纵模输出,对种子注入锁定的TEA CO_2激光器进行了研究。首先,本文提出了一种透射耦合输出的虚共焦非稳谐振腔方案,利用Glad软件的Prony法对腔模的演化进行了仿真分析,并实验记录了近场与远场的光斑光强分布。仿真结果与实验结果吻合,验证了此腔型方案的合理性。其次,在此腔型的基础上进行了腔外种子注入锁定实验,实验结果显示:自由振荡时存在频率为195 MHz的拍信号,当种子注入锁定成功后,输出激光拍频消失,波形变光滑,峰值功率降低48.6%,脉冲产生时间缩短20ns。实验结果与已有成果吻合,验证了此种透射式非稳腔的TEA CO_2激光器具有输出高质量单纵模的能力。     

A multibeam radio-frequency ion source with a discharge chamber inside a resonator

The design of a multibeam ion source with a discharge chamber inside a half-wavelength radio-frequency (RF) resonator with a spiral load is described. The resonator is excited by a loop insulated from the body of the resonator. The RF oscillator operating at a frequency of 38 MHz is grounded. The use of the resonator facilitates the initiation of a discharge at a low power level. The amplitude-frequency characteristics of the resonator at the operating frequencies of the ion source are presented. The effect of the RF power and the extracting voltage on the ion-beam current has been studied. The experimental results on the ion-beam extraction at a low RF power (<100 W) are presented.     

异质微环谐振腔双稳态及全光存储器应用

提出了一种基于异质集成波导的微环谐振腔,对其双稳态现象进行了研究分析,并将其应用于全光存储功能的实现。异质集成波导具有超高的克尔非线性效应,不受热光效应和载流子响应的限制,在超快克尔非线性效应的支持下,该结构具有快速全光切换的能力。设计了一个高品质因子Q = 77565的微环谐振腔,用耦合模式理论模拟了其双稳态现象。在峰值功率为474 fJ,宽度为20 ps的脉冲激励下,该微环谐振腔很好地实现了全光存储功能,并通过波分复用的串联微环结构展示了波长可寻址的四位光存储器。研究了基于超高克尔非线性效应的双稳态现象,为实现超快切换速度提供了可能性,在光存储、光开关、人工智能研究等方面具有一定的参考价值。     

压电振动电阻尼与能量转换特性研究

根据压电构造方程和振动原理,建立压电振动能量收集的耦合场动力学模型。详细推导电阻尼与外接电阻和机电耦合系数之间的数学关系,并揭示外接电阻对系统固有弹性的作用效果。通过数值模拟研究电阻尼特性对谐振频率、振动幅值和功率的影响关系,并从能量转换效率的角度分析优化电阻与最大输出功率的关系。分别对多种外接电阻条件下压电梁的输出电压及功率进行实验测试,实验结果表明,电阻尼导致压电梁的谐振频率发生偏移,其大小与外接电阻值成正比,而且在外接优化电阻时输出功率最大。     

Y分支LiNbO3波导的单模特性的测试方法研究

光纤陀螺中使用的Y分支相位调制器对单模特性要求非常高.文中深入研究了Y分支波导的多模特性,在理论分析的基础上用BPM做了Y分支的设计和仿真,模式耦合分析表明,当Y分支波导为多模时,其倒置输入时的输出功率会随波长变动发生周期性波动,该特征可用于定量判定多模临界波长.归纳数据,提出了一种独特的通过Y分支输出功率曲线测定其多...     

Characterization of whispering gallery mode slow light in microspheres

A slow-light system composed by a microsphere resonator and a section of bitapered fiber is characterized theoretically in this article. Theoretical analysis and numerical simulation on the input and output characteristics and the transmittivity of the microsphere resonator were carried out. The directional coupling theory was used to analyze the input/output characteristics of single microsphere resonator and parameters in the overcoupling state, including the relationships between the effective phase shift, transmittivity, effective time delay, light velocity, and the speed of light. The coupling coefficient distance was studied by theoretical analysis and numerical simulation. The theoretical analysis and simulation optimization of the slow-light gyroscope were carried out to obtain the optimized radius of microsphere resonator and distance between microsphere resonator and bitapered fiber. Through theoretical investigation and mathematical simulation, transmission characteristics and time delay mathematical expressions of the microsphere resonator were obtained. Theoretical analysis and simulation of the fiber optic gyroscope sensitivity showed that slow-light improved the accuracy of the interferometric fiber optic gyroscope.     

对准误差对半球谐振陀螺仪输出精度的影响

通过误差机理分析以及在单轴速率转台上的标定试验,分析了半球谐振陀螺仪的激励器和位移传感器对准误差对输出精度的影响.利用环形谐振子的运动方程,得出了在对准误差的情况下谐振子的径向振动方程.根据半球谐振陀螺仪闭环检测原理,计算了陀螺仪输出角速率的误差.计算结果表明,对准误差将产生与角速率平方项有关的误差,导致陀螺仪输出非线性.在单轴速率转台上进行了标定试验,验证了输出中存在与速率平方项有关的误差,并针对克服此项误差进行了一些探讨.     

基于Cantor结构的一维光子晶体耦合腔的光学特性

在N=3的三分Cantor多层结构的基础上设计了一种光子晶体耦合腔结构,用传输矩阵法研究了这种耦合腔结构的光学特性。结果表明,新结构有更宽的带隙,并在宽带隙中出现了一个损耗非常小的超窄透射窗口;保持缺陷层的几何厚度不变,改变缺陷层介质的折射率,该透射窗口位置能在很大的范围内移动。这种新的耦合腔结构可用作超窄带光子晶体滤波器或波长可调谐滤波器,在光通信超密集波分复用和光学精密测量等领域中有应用价值。     

差动式石英谐振力传感器

】利用ＡＴ切型的厚度剪切石英晶体谐振器沿不同方向施加外力时,将会获得不同的灵敏度这一特点,本文研究了一种新型的差动石英谐振式力敏传感器。将两个同频率的敏感石英谐振器以对称简支方式固定在传感器内,使外力分别沿两个敏感谐振器的ｘ轴和ｚ′轴作用,产生两个方向相反的频率变化,通过电路混频,形成差动输出。分析结果表明,采用这种差动方式将使传感器性能得到明显提高。