宽光谱光栅侧面耦合集光技术研究

发布时间：2018-06-17 15:27

本文选题：亚波长光栅 + 侧面耦合技术　；参考：《浙江大学》2015年硕士论文

【摘要】：利用光栅侧面耦合技术多为单波长或窄带光耦合,用于光纤激光器泵浦、光波导集成等领域,而用于可见光宽带耦合的研究很少。通过在波导上集成亚波长衍射光栅结构,可以引导太阳光在波导的侧面进行出光汇集,因此可以作为一种新型的太阳能集光器结构。本文主要就是研究这种基于光栅侧面耦合的宽光带集光技术。在理论分析中,除了对光栅耦合原理进行了阐述,还详述了矢量衍射理论中的时域有限差分法和严格耦合波法,并分别对其麦克斯韦方程组进行了求解,为之后的光栅结构优化仿真等内容奠定了理论基础。亚波长光栅结构参数影响衍射耦合效率,从而影响波导侧面收集的能量。通过FDTD软件对光栅结构参数进行扫描仿真,再利用快速下降法获得不同类型不同面形的最佳光栅结构,并利用RCWA法对其中的矩形相位光栅结构进行了验证。不同的入射角对集光器影响较大,因此本文对不同入射角下的衍射耦合效率也进行了仿真分析。耦合光在波导内通过全反射传播,当光传播到波导与光栅的交界面处发生透射衍射,造成能量的泄露。利用FDTD软件对几种耦合波长下的一次传播泄露进行了计算,并在矩形相位光栅中,对耦合波长为420nm的最大传播距离以及侧面耦合的能量与波导长度的关系进行了计算分析。由于光传播损失严重,对高对比度的金属光栅提出了改进方案。
[Abstract]:The side-coupling technology of grating is mostly single-wavelength or narrow-band optical coupling, which is used in the fields of fiber laser pumping and optical waveguide integration. However, there is little research on wide-band coupling of visible light. By integrating the subwavelength diffraction grating structure on the waveguide, the solar light can be induced to collect light on the side of the waveguide, so it can be used as a new type of solar collector structure. In this paper, we mainly study the wide-band light collecting technology based on grating side-coupling. In the theoretical analysis, in addition to explaining the principle of grating coupling, the finite difference time-domain method and the strictly coupled wave method in vector diffraction theory are described in detail, and their Maxwell equations are solved respectively. It lays a theoretical foundation for the optimization and simulation of grating structure. The structural parameters of the subwavelength grating affect the diffraction coupling efficiency, thus affecting the energy collected on the side of the waveguide. The structural parameters of the grating are scanned and simulated by FDTD software. The optimal grating structures with different types and different plane shapes are obtained by using the fast descent method, and the rectangular phase grating structure is verified by the RCWA method. The diffractive coupling efficiency at different incident angles is also simulated and analyzed. The coupled light propagates through the total reflection in the waveguide, and when the light propagates to the interface between the waveguide and the grating, the transmission and diffraction take place, which results in the energy leakage. The primary propagation leakage at several coupling wavelengths is calculated by using the FDTD software. The relationship between the maximum propagation distance of the coupled wavelength and the side coupling energy and the waveguide length in rectangular phase grating is calculated and analyzed. Due to the serious loss of light propagation, an improved scheme for high contrast metal gratings is proposed.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TK513.1;TN253

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