Box-like spectral response of 2-D microring resonator arrays

In terms of the coupled mode theory and the transfer matrix technique, novel formulas of the transfer functions are presented for a 2-D microring resonator array. By using these formulas, transmission characteristics are analyzed for this kind of Si based polymer device. Simulation shows that by means of parallel-cascading multiple microrings in every filter element, the passband can be flattened, and the box-like spectral response can be formed; in terms of series-cascading such several filter elements, the passband becomes precipitous, and the non-resonant light and the crosstalk become weak.     

同轴-三平板型水介质脉冲输出开关实验研究

设计了用于脉冲功率装置的4 MV水介质同轴 三平板型输出开关。该脉冲功率装置将由24路相同的独立模块组成，每路模块由Marx发生器、中间储能器、激光触发气体开关、脉冲形成线、水介质脉冲输出开关、脉冲传输线等组成。水介质脉冲输出开关是同轴 三平板结构水介质多通道自击穿开关，由输入输出电极、预脉冲屏蔽板和连接部件组成。进行了有预脉冲屏蔽板结构和无预脉冲屏蔽板结构的自击穿水开关实验研究。有预脉冲屏蔽板结构开关的输入、输出电极都是半球电极，直径分别是8 cm和5 cm；无预脉冲屏蔽板结构开关为针 板结构，输入电极为平板电极，输出电极为直径3 cm的电极棒。Marx发生器充电70 kV，开关的击穿电压为3 MV，放电电流为450 kA。在3 MV等级的击穿电压下，有预脉冲屏蔽板结构开关的抖动约6 ns，没有预脉冲屏蔽板结构开关的抖动减小至3 ns。     

高斯反射率输出镜改善光束质量的实验研究

非稳腔能产生大体积基模,具有好的空间选模特性,但在固体调Q激光器中,由于孔径光阑和热畸变的影响,非稳腔输出的横模并不光滑.使用高斯反射率耦合输出镜可较好地改善其输出光束质量,设计了平-凸非稳腔,使用Nd:YAG,电光调Q固体激光器进行实验,获得了较为平滑的远场光强分布,实验结果表明高斯反射率输出镜可较好地改善固体激光器中非稳腔输出光束质量.     

Edge-pumped, folded zig-zag Nd:YAG slab laser

 We report the design and performance of conduction-cooled, edge-pumped, folded zig-zag continuous wave Nd:YAG slab laser. The Nd:YAG slab is pumped with waveguide coupled laser diode bars. The coupling efficiency of waveguide to laser diode radiation is 97%. In a folded zig-zag resonator, a maximum output power of 37 W in multimode operation is achieved for an incident pump power of nearly 180 W on the Nd:YAG slab. This corresponds to an optical-to-optical conversion efficiency of 20% and slope efficiency of 32%. We obtained more than 10 W of output power with the beam quality factors in the width dimension and in the thickness dimension equal to 8.     

用波尔共振仪研究受迫振动特性

介绍了波尔共振仪实验系统的基本结构及原理,测定了幅频和相频特性曲线,分析了实验系统误差.研究发现,当系统发生共振时,驱动频率和固有频率近似相等且相位差为90°.     

Rectangular loop-gap resonator with the light access to the sample

A modified rectangular loop-gap resonator for X-band electron paramagnetic resonance (EPR) studies of aqueous samples, enabling the light access, is described. Changes introduced into rectangular resonator geometry, previously presented in Piasecki et al. (1998) [1], and redesigned coupling structure lead to the better thermal and mechanical stability. The modified structure makes provision for the controlled light access to the sample placed in a flat cell during an EPR experiment. The sensitivity of the resonator for aqueous samples as well as an experimentally tested microwave magnetic field homogeneity are presented. Results of simulations and experimental tests indicate that the presence of light access holes in the resonator's front side does not disturb the uniformity of microwave magnetic field distribution in the nodal plane. The optimal flat cell thickness for unsaturable and saturable aqueous samples has been calculated for this new structure. A modified rectangular geometry of the loop-gap resonator ensures a good performance for aqueous samples allowing its convenient and efficient light illumination during EPR signal recording .     

带有环形谐振器的1×2光子晶体功率分配器传输性能

 利用正方格2维光子晶体设计了带有环形谐振器的1×2光子晶体功率分配器结构,该结构具有1个输入端口和2个输出端口。采用时域有限差分法研究了该功率分配器对电磁波的传输性能,结果表明：其结构在第三通信窗口(1 550 nm波长)实现了电磁波的高效传输,同时具有优良的电磁波通频带功率二等均分性,以及电磁波传输转向设计灵活、损耗低、结构紧凑等优点。     

基于二维质点振动模型的半球谐振陀螺谐振子进动分析

半球谐振陀螺是基于固体波的进动效应进行角速度检测的一种全固态陀螺。为分析半球谐振子中固体波的进动效应,基于虚功原理,建立了理想条件下半球谐振陀螺谐振子中固体波进动的动力学模型。针对进动波的动力学模型过于复杂、难于分析的缺陷,提出采用相似系统的分析方法,将该动力学模型等效为二维空间质点的简谐振动模型;采用快变量与慢变量分离的方法,对等效模型进行了参数分析,通过与实际的半球谐振陀螺信号处理系统采集的李沙育图形进行对比,验证了等效简谐振动模型的有效性和正确性。     

微环谐振腔实现倍频效应的带宽分析

谐振腔能以较低的输入功率获得较高的非线性转换效率,其代价是带宽方面的限制,围绕微环谐振腔实现倍频效应中影响转换效率的因素,分析了耦合系数、折射率变化、相位失配等对转换带宽的影响,讨论了基于AlGaAs的人工双折射微环谐振腔实现基频光波波长为1840 nm时倍频效应的转换带宽.     

Characterization and improvement of absorption and scattering by profiled architectural surfaces without specialized test facilities

A turntable apparatus and measurement procedure, based on ISO 17497-1, were developed for measuring the random-incidence absorption and scattering of surfaces, without specialized facilities. While not highly accurate, they proved adequate for determining the general characteristics of surfaces. Two original profiled wooden architectural surfaces, and a hard, flat reference surface, were characterized, and found to have low absorption and scattering. They were then modified for increased absorption by creating Helmholtz-resonator configurations, obtaining good performance at low- and mid-frequencies. They were also modified for increased scattering, in one case by creating a Schroeder diffuser. In the other case, the surface was integrated into a novel frame-array configuration, which scattered sound very well above 500 Hz.