Appl Opt. 2023 Mar 20;62(9):2376-2385. doi: 10.1364/AO.483184.
There have been significant research and analyses on the diffraction efficiency and characteristics of spectral grating with a wavelength-scale period. However, thus far an analysis on a diffraction grating with an ultra-long pitch over several hundred times of the wavelength (>100µ) and a very deep groove over dozens of micrometers has not been performed. We analyzed the diffraction efficiency of these gratings by using the rigorous coupled-wave analysis (RCWA) method and confirmed that the RCWA analytic results correspond well to the actual experimental results on the wide-angle beam-spreading phenomenon. In addition, because a long-period grating with a deep groove results in a small diffraction angle with relatively uniform efficiency, it is possible to convert a point-like distribution to a linear distribution for a short working distance and a discrete distribution for a very long working distance. We believe that a wide-angle line laser with a long grating period can be used in various applications, such as level detectors, precision measurements, multi-point light detecting and ranging (LiDAR) light sources, and security systems.
已经有大量关于具有波长级周期的光谱光栅的衍射效率和特性的研究和分析。然而，到目前为止，还没有对具有数百倍于波长（>100µ）的超长节距和数十微米深的凹槽的衍射光栅进行分析。我们使用严格耦合波分析（RCWA）方法对这些光栅的衍射效率进行了分析，并确认 RCWA 分析结果与宽角光束扩展现象的实际实验结果非常吻合。此外，由于具有深槽的长周期光栅导致衍射角较小且效率相对均匀，因此可以将点状分布转换为短工作距离的线性分布，以及非常长工作距离的离散分布。我们相信，具有长光栅周期的广角线激光器可以用于各种应用，例如水平探测器、精密测量、多点光探测和测距（LiDAR）光源以及安全系统。
