相位共轭光腔的热稳性

使用传播矩阵方法推导出了相位共轭腔的热稳条件,指出仅满足G_1G_2=(1/2)并不意味着相位共轭腔一定是热稳的.因此,为得到高质量的输出激光束,需进行相位共轭腔的最佳设计.用本文所得结果还能解释利用相位共轭技术消除畸变的定域性现象.     

圆形球面虚共焦非稳腔的三维数值研究

 通过对1/2共焦腔和稳定腔的计算,考查了同三维菲涅耳积分方程相应的C 8程序的可靠性。对激光在三维圆形球面虚共焦非稳腔中的传输作了计算和分析。取相同的远场传输距离且放大率由大变小时，强度分布由近场的投影分布逐渐趋于远场的高斯、超高斯分布。     

90°束转动环形非稳腔模场数值分析

用矩阵方法导出了ＵＲ９０（ｕｎｓｔａｂｌｅｒｉｎｇｒｅｓｏｎａｔｏｒｗｉｔｈ９００１６７ｂｅａｍｒｏｔａｔｉｏｎ）环形非稳腔的衍射积分方程，获得了腔的等价菲涅耳数Ｎｅｑ的关系公式，分析了反向模的抑制方法并给出反向模抑制镜的曲率半径，通过数值计算的方法阐明了腔模本征值与放大因子Ｍ的变化关系，当腔的放大因子Ｍ＝１．２时，得到了腔的模场分布曲线。     

约瑟夫森结(阵列)与谐振器的耦合效应研究

利用一种新的电路模型系统研究了约瑟夫森结(阵列)与谐振器的耦合效应.以结的电压自锁定台阶幅度ΔI为目标值,得到了谐振电路的电阻R、谐振频率fr对耦合的影响规律,并给出了合理解释;以结阵列的相位互锁定强度IL为目标,研究了IL对锁定电压VL的依赖关系,同时,通过相关计算将其与通常电路模型下得到的结果进行了比较.     

嵌入到Fabry-Perot谐振腔的双晶约瑟夫森结阵列的阻抗匹配和相位锁定研究

在He等人所做的嵌入到Fabry-Perot谐振腔中约瑟夫森结阵列的微波辐照研究基础上,提出了同时实现约瑟夫森结阵列阻抗匹配和相位锁定的方法,进行了相关的电磁仿真和数值计算.双晶约瑟夫森结阵列被制作在YSZ双晶基片上,同时被嵌入到Fabry-Perot谐振腔内.通过在基片上制作与结阵列集成的串联馈电半波偶极天线阵,并对其结构进行优化实现了结与天线的匹配,数值计算表明结的辐射效率达到94%;利用天线阵辐射场的特征和对模型合理的设计,使Fabry-Perot谐振腔和基片同时谐振在合适的模式下,从而使结阵列与谐 关键词： 约瑟夫森结阵列 阻抗匹配 相位锁定 Fabry-Perot谐振腔     

一种基于光子晶体异质结构的新型多通道波分复用器

在二维三角光子晶体环形腔的周围增加六个散射介质柱,构成一个新的环形腔结构,该结构使光波的透射率达到90%,带宽也比较小。通过改变光子晶体介质柱的折射率,使环形腔的选择波长不断改变,能够明显地区分出两个不同波长,且分波波长在通信波长范围之内。将不同折射材料的光子晶体连接在一起,构成一种新的光子晶体波分复用器,相比同种材料,它具有高效率,多波长选择的优点。利用这种异质结构可以构建一个多波长的波分复用结构,它也为制作多通道波分复用器奠定了基础。     

介质不均匀性对激光模式相位与光强分布的影响

将不均匀介质势函数进行泰勒展开,取其前3项近似,与描述光腔模式的亥姆霍兹方程中的特殊函数结合,根据光腔边界条件推导出光腔模式的本征解、激光输出功率以及不均匀介质与激光模式的相位与强度分布关系表达式。将表达式应用于氧碘化学激光器的功率与输出耦合率的非线性拟合以及近场光强分布的分析,预测趋势与文献结果相符。     

基于硅基槽波导的单纤三向滤波器的研究

设计了基于硅基槽波导的微环谐振型单纤三向滤波器。基于电磁场理论得到了二维情形下的硅基槽波导的模场及有效折射率随波长的变化关系,在此基础上,利用硅基槽微环谐振腔谐振波长与微环半径的关系,优化得到了可将1490nm和1550nm两个下载波长分开的谐振环半径,并同时将1310nm波长上传,三个波长信号从不同端口输出,成功地实现了三向器滤波功能。利用传递函数法模拟了所设计的硅基槽微环谐振型三向滤波器的输出光谱,结果显示其串扰可低至-16.9dB。     

Novel Helmholtz-based photoacoustic sensor for trace gas detection at ppm level using GaInAsSb/GaAlAsSb DFB lasers

A new and compact photoacoustic sensor for trace gas detection in the 2-2.5 microm atmospheric window is reported. Both the development of antimonide-based DFB lasers with singlemode emission in this spectral range and a novel design of photoacoustic cell adapted to the characteristics of these lasers are discussed. The laser fabrication was made in two steps. The structure was firstly grown by molecular beam epitaxy then a metallic DFB grating was processed. The photoacoustic cell is based on a Helmholtz resonator that was designed in order to fully benefit from the highly divergent emission of the antimonide laser. An optimized modulation scheme based on wavelength modulation of the laser source combined with second harmonic detection has been implemented for efficient suppression of wall noise. Using a 2211 nm laser, sub-ppm detection limit has been demonstrated for ammonia.     

Preliminary study of a niobium quarter-wave prototype cavity for a heavy-ion superconducting linac

Superconducting quarter-wave resonators,due to their compactness and their convenient shape for tuning and coupling,are very attractive for low-β beam acceleration.In this paper,two types of cavities with different geometry have been numerically simulated the first type with larger capacitive load in the beam line and the second type of lollipop-shape for 100 MHz,β=0.06 beams then the relative electromagnetic parameters and geometric sizes have been compared.It is found that the second type,whose structural design is optimized with the conical stem and shaping drift-tube,can support the better accelerating performance.At the end of the paper,some structural deformation effects on frequency shifts and appropriate solutions have been discussed.