The optical transmission of resonant guided-mode gratings patterned on suspended silicon nitride thin films and illuminated at normal incidence with a Gaussian beam is investigated both experimentally and theoretically. Effects due to the beam focusing and its finite size are accounted for by a phenomenological coupled-mode model whose predictions are found to be in very good agreement with the experimentally measured spectra for various grating structures and beam sizes, and which allow for a detailed analysis of the respective magnitude of these effects. These results are highly relevant for the design and optimization of such suspended structured films that are widely used for photonics, sensing, and optomechanics applications.

中文翻译：

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悬浮谐振导模光栅的准直和有限尺寸效应

在实验和理论上研究了在悬浮氮化硅薄膜上图案化并用高斯光束以法向入射照射的谐振导模光栅的光学传输。由于光束聚焦及其有限尺寸的影响由现象学耦合模式模型解释，该模型的预测与各种光栅结构和光束尺寸的实验测量光谱非常一致，并允许进行详细分析这些影响的相应幅度。这些结果与这种广泛用于光子学、传感和光机械应用的悬浮结构薄膜的设计和优化高度相关。