共查询到20条相似文献,搜索用时 0 毫秒
1.
A novel polarisation-independent optical circulator, which employs two fibre-optic polarising beam splitters and two yttrium-iron-garnet (YIG) spherical lenses, is reported. The present structure has the advantage of low-loss splicing with other single-mode fibres. The insertion loss was 2.5 dB at 1.30 ?m wavelength, and was almost independent of the incident polarisation angle. The backward attenuation was more than 18 dB. 相似文献
2.
Tao Liu A.R. Zakharian M. Fallahi J.V. Moloney M. Mansuripur 《Photonics Technology Letters, IEEE》2005,17(7):1435-1437
A compact polarizing beam splitter based on a photonic crystal (PC) directional coupler with a triangular lattice of air holes is designed and simulated. In the employed PC structure, transverse-electric (TE) light is confined with the photonic bandgap effect, while transverse-magnetic (TM) light is guided through an index-like effect. Due to the different guiding mechanisms, TM and TE light have strikingly different beat lengths, which is utilized to separate the two polarizations in a directional coupler no longer than 24.2 /spl mu/m. The two-dimensional finite-difference time-domain method of computation is used to evaluate the device performance. The extinction ratios are found to be around 20 dB for both TE and TM polarized light. 相似文献
3.
4.
5.
6.
7.
偏振和位相调控分光膜是自由空间量子通信系统中不可缺少的光学元件,其性能直接影响通信质量,决定通信误码率。基于等效层设计理论,采用“介质+金属+介质”的特殊膜系结构,选用Ag金属和SiO2、Al2O3、Ta2O5三种介质膜料作为镀膜材料,实现石英衬底45°入射时,1500~1600 nm波段消偏振平均透射/反射比为8.5:91.5,在1530、1540、1550、1560 nm控制位相的分光膜。采用电子束蒸发离子辅助沉积技术,优化沉积工艺,制备了分光膜样品。检测结果表明:在45°入射条件下,1500~1600 nm波段光谱平均透射/反射比为8.53:91.47,在1530、1540、1550、1560 nm处透射光位相差控制在5.02°以内,反射光位相差控制在8.05°以内,满足通信系统分光比及位相控制的要求。此外,该分光膜通过了相应的环境试验测试,满足可靠性要求。 相似文献
8.
Morita N. Tanaka T. Yamasaki T. Nakanishi Y. 《Antennas and Propagation, IEEE Transactions on》1968,16(6):724-727
The theoretical analysis of the scattering of a beam wave by a small spherical object, which exists at the neighborhood of the beam waist on the propagation axis, is treated. In this analysis, the property of a spherical object is generalized so as to have anr -dependent dielectric constant. Through numerical calculations for the case of the conducting sphere, the difference between the scattering of a beam wave and that of a plane wave are discussed. 相似文献
9.
通过设计由介质薄膜组成的二周期结构,在特定的入射条件下,利用特征矩阵的方法计算了TE光和TM光的透射率,发现该结构对TE光和TM光存在一系列分离的频率通道。这些分离的频率通道使该结构既可以用作频率滤波器,又可以用作偏振分束器。 相似文献
10.
11.
Symmetrical fully-etched and chirped beam splitter based on a subwavelength binary blazed grating 下载免费PDF全文
A novel symmetrical chirped beam splitter based on a binary blazed grating is proposed, which adopts the fully-etched grating structure compatible with the current fabrication facilities for CMOS technology and convenient for integration and manufacture process. This structure can realize nearly equal-power splitting operation under the condition of TE polarization incidence. When the absolutely normal incidence occurs at the wavelength of 1580 nm, the coupling efficiencies of the left and the right branches are 43.627% and 43.753%, respectively. Moreover, this structure has the tolerances of 20 nm in etched depth and 3?in incident angle, which is rather convenient to manufacture facility. 相似文献
12.
The radiation pattern of a sphericai layered dielectric lens is computed using eigenfunction expansions. The method is an adaptation of the well-known classical solution for plane wave scattering from a layered sphere but uses the less well-known vector addition theorem for spherical wave functions to represent the off-center sources. The usefulness of this formulation is that the solution is analytical and "exact," and is an efficient tool for investigating spherical lens radiation properties. The method is illustrated for a typical Luneburg lens. 相似文献
13.
14.
15.
16.
为了设计单个椭球面缩束(扩束)透镜,采用全面学习策略的粒子群算法作为设计方法,依据光线折射定律矢量形式所表征的椭球面折射特性进行了理论分析,得到了用全面学习策略的粒子群优化算法设计单个椭球面缩束(扩束)透镜的适应度数据公式,设计出了线度小于170mm缩束14.16倍的单个椭球面缩束透镜,并用光线追迹方法模拟了缩束或扩束过程。结果表明,单个椭球面透镜可以起到缩束或者扩束作用,全面学习策略的粒子群算法可用于椭球面缩束透镜的设计。这一结果对于简化扩(缩)束系统结构、设计出适应于不同要求的单个扩(缩)束透镜是有帮助的。 相似文献
17.
利用广义惠更斯-菲涅尔衍射积分,并考虑球差的影响,对超高斯光束通过球差透镜后的传输特性作了数值计算和讨论。本文所得主要结果对实际光学系统的设计是在用的。 相似文献
18.
An optical frequency shifter making use of the electro-optic effect in LiNbO3 was built to shift the Fourier spectrum of a mode-locked He-Ne laser; the shift was continuously adjustable from -45 GHz to +45 GHz about the central optical frequency of 473.61 THz. Shifted Fourier spectra recorded with a scanning Fabry-Perot interferometer were found to be in excellent agreement with theory. 相似文献
19.
We give a comprehensive representation of the Wolf effect in propagation both in free space and after a lens for an outstanding class of partially coherent beams, namely Gaussian Schell-model beams. We characterize the correlation-induced spectral changes, throughout the whole space, by means of isoshift lines and transverse shift profiles. The maximum value of the frequency blueshift, occurring on the optical axis, is also calculated 相似文献
20.
本文系统地研究了球面端面的锥形发散梯度折射率纤维透镜的几何光学设计理论以及用作激光束变换元件的设计规律。 相似文献