常系数线性微分方程RMI解题机

本文介绍的常系数线性微分方程解题机是利用数学方法论的研究成果，摸拟人的数学思维过程，采用关系映射反演（ＲＭＩ）方法，通过符号推理给出微分方程解析解的数学软件．文中介绍了研制该解题机的基本思想和实现技术，并给出了用解题机求解微分方程和微分方程组的几个实例．     

Metal-mirror-based grating for high-efficiency element in dense wavelength division multiplexing

It is desirable to obtain high efficiency with polarization-independence and wideband properties for incident wavelength. A metal-mirror-based grating is presented to diffract the incident wave into reflection orders with high efficiency for TE and TM polarization. The modal method and rigorous coupled-wave analysis (RCWA) are used together to optimize a metal-mirror-based grating effectively. From the analysis of the modal method, it is feasible to realize such a grating with the prescribed grating duty cycle and period. Accurate parameters of the grating depth and thickness of the connecting layer are optimized using RCWA. Compared with the reported binary simple grating, high efficiency can be improved greatly for the incident wavelength of 1550 nm in dense wavelength division multiplexing. The diffraction investigation indicates that a wideband property for incident wavelength can be obtained for such a novel metal-mirror-based grating.