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排序方式: 共有8687条查询结果,搜索用时 15 毫秒
911.
本文介绍了两种热电偶冷端温度补偿电路在物理实验测量中的应用及校准方法,对热电偶的工作原理、冷端温度补偿必要性作了说明,并详细介绍了冷端温度补偿过程. 相似文献
912.
A multifunctional integrated microfluidic biochip device was engineered to estimate the activity-toxicity and composition principle of medicine in a cell model in vitro. 相似文献
913.
Yu-jun Quan Pei-de Han Qi-jiang Ran Fan-ping Zeng Li-peng Gao Chun-hua Zhao 《Optics Communications》2008,281(11):3105-3110
A photonic wire-based directional coupler based on SOI was fabricated by e-beam lithography (EBL) and the inductively coupled plasma (ICP) etching method. The size of the sub-micron waveguide is 0.34 μm × 0.34 μm, and the length in the coupling region and the separation between the two parallel waveguides are 410 and 0.8 μm, respectively. The measurement results are in good agreement with the results simulated by 3D finite-difference time-domain method. The transmission power from two output ports changed reciprocally with about 23 nm wavelength spacing between the coupled and direct ports. The extinction ratio of the device was between 5 and 10 dB, and the insertion loss of the device in the wavelength range 1520-1610 nm was between 22 and 24 dB, which included an about 18.4 ± 0.4 dB coupling loss between the taper fibers and the polished sides of the device. 相似文献
914.
In the present work, four-layer polymeric waveguides have been fabricated and characterized by interchanging the film layer. Using polyvinyl alcohol (PVA) and styrene acrylonitrile (SAN) polymer it has been shown that polymers do not loose their own property in multilayer structure and better efficiency can be achieved in the form of low propagation losses and mode filtration. Due to high contrast of PVA and SAN films, a broad spectrum of refractive index in four-layer structure has been achieved. 相似文献
915.
Crossed waveguide is widely used in optical devices, whose excess loss has a strong impact on multi-turn optical waveguide ring resonator and resonator integrated optic gyro. The resonance curve of the ring resonator is sharply dependent on the loss within the resonator. This paper presents how to get excess loss of the crossed waveguides nondestructively through the comparison of the resonance characteristics between one-turn and multi-turn optical waveguide ring resonators. 相似文献
916.
Mukesh Kumar Alaria A. K. Sinha A. Bera V. Srivastava 《International Journal of Infrared and Millimeter Waves》2008,29(12):1083-1090
The main objective of the paper is to make an efficient design of the input and output coaxial coupler for a helix TWTs. An
approach has been developed for the efficient design and analysis of the coaxial couplers in the practical situation. Normally
multi-section impedance transformer approach is used for any wide band coupler. For a space helix TWT, coupler should be wide
bandwidth and small size. In this case coupler is matched with helix slow wave structure and the standard 50-ohm connectors.
The simulated return loss (dB) profile for different type of couplers is obtained by using Ansoft HFSS, CST microwave studio
and compares those with experimental results. The tip loss design at sever ends for the input and the output section has been
also optimized. 相似文献
917.
Dan Zhang Hongting Jia Kiyotoshi Yasumoto 《International Journal of Infrared and Millimeter Waves》2008,29(9):823-831
A problem of coupling between conventional dielectric waveguides and a two-dimensional photonic crystal waveguide is analyzed,
using the Fourier series expansion method combined with the absorbing boundary condition of a perfectly matched layer (PML).
A novel structure for the input and output ends of the photonic crystal waveguide is proposed to increase the coupling efficiency.
Numerical examples are demonstrated and discussed to validate the effectiveness of the proposed structure. 相似文献
918.
919.
导模共振滤波器由于其高峰值反射率,低旁带反射,窄带以及带宽可控等优良特性引起了人们极大的关注,采用亚波长光栅的导模共振效应可以实现传统基于高低折射率介质的多层膜滤波器所无法实现的特殊功能,在弱调制模式下,其共振带宽可以被压缩到零点几纳米,但是由于介质表面和空气层的菲涅耳反射,使得偏离或者远离共振区时的反射率偏高,根据等效介质理论,亚波长光栅在远离共振区可以被看为均匀的薄膜,本文通过对导模共振光栅进行单层、双层以及三层抗反射设计,有效的降低了导模共振光栅的旁带反射率,从而在可见光波段获得了性能优良的共振滤波
关键词:
导模共振
平面波导
傅里叶模式理论
窄带滤波 相似文献
920.