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，作为一种新型的太阳能集光器结构。利用时域有限差分算法软件(FDTD)对光栅结构进行仿真，以获得最大衍射效率的光栅结构参数，并对不同入射角度下的衍射耦合效率进行了分析。结果显示，在宽波段的光谱范围内，以上光栅结构均达到较好的衍射效率，其中闪耀光栅衍射效率最大，其衍射效率可达48.8%。这种利用亚波长衍射光栅结构的小型集光器有望应用在有关太阳能能量的收集应用中，例如照明、太阳能电池等。

The technology of grating side-coupling is often applied in such fields as coupling of light of single wavelength or narrow waveband, pump of fiber laser, integration of optical waveguide, but its application for broadband coupling of visible spectrum is rarely studied. Sunlight can concentrate and output at the edge of waveguides by integrating sub-wavelength gratings with waveguides, making it a novel solar concentrator. In this paper, different grating structures with the Finite Difference Time Domain(FDTD) solution software were simulated to obtain the optimal structure design. Besides, the angle of light for the coupling-efficiency was also discussed. The result demonstrates that the structures mentioned above all feature good diffractive efficiencies in broadband wavelength, among which the blazing grating reaches the largest efficiency, namely 48.8%. This kind of sub-wavelength gratings feature integration of small size, which makes it promising in absorption of solar energy, such as lumination, photovoltaic cell, etc.