Shi Xiaogang, Shen Hong, Xue Zhenghui, Wang Bingjie
Appl Opt. 2022 Aug 20;61(24):7245-7254. doi: 10.1364/AO.462563.
Color non-uniformities caused by a dispersion effect can seriously affect the image quality for a diffractive waveguide display system. In this work, we propose a subwavelength multilayered dielectric grating structure by a rigorous coupled wave analysis as a novel coupling grating, to the best of our knowledge, for waveguide-based near-eye displays to overcome the "rainbow" effect. Such a grating structure exhibits a tunable high-efficiency resonance in first-order diffraction due to resonant coupling of incident light with the grating structure. A further analysis of the resonant behaviors helps us get a clear understanding of the underlying physics for the mode excitation and resonant coupling process. The first-order resonance with a diffraction efficiency of more than 60% can be achieved with the resonant angle continuously shifted to get a large field of view. The resonant angle, diffraction efficiency, and spectral linewidth can be easily tuned by the geometrical parameters of the grating structure.
由色散效应引起的颜色不均匀会严重影响衍射波导显示系统的图像质量。在这项工作中，据我们所知，我们通过严格耦合波分析提出了一种亚波长多层介质光栅结构，作为一种新型耦合光栅，用于基于波导的近眼显示器，以克服“彩虹”效应。这种光栅结构由于入射光与光栅结构的共振耦合而在一阶衍射中表现出可调谐的高效共振。对共振行为的进一步分析有助于我们清楚地理解模式激发和共振耦合过程的潜在物理原理。通过连续改变共振角以获得大视场，可以实现衍射效率超过60%的一阶共振。共振角、衍射效率和光谱线宽可以通过光栅结构的几何参数轻松调整。
