Bark Hyeon Sang, Kim Seong-Han, Ji Young Bin, Kwon Jae Gwang, Kang Chul, Baek In Hyung, Lee Kitae, Oh Seung Jae, Jeon Tae-In, Kee Chul-Sik
Divison of Applied Photonics System Research, Advanced Photonics Research Institute, GIST, Gwangju, 61005, Republic of Korea.
Radiation Center for Ultrafast Science, Korea Atomic Energy Research Institute, Daejeon, 34057, Republic of Korea.
Sci Rep. 2024 Dec 2;14(1):29974. doi: 10.1038/s41598-024-80501-3.
We investigated an asymmetric slab grating structure to achieve significant tuning of the quality (Q) factor for a leaky mode while minimizing frequency variation. This structure comprises two identical gratings placed on the top and bottom of a slab waveguide, with one grating laterally shifted to introduce asymmetry. Simulations demonstrate that lateral shifting of one grating induces extensive changes in the Q-factor with minimal frequency variation, particularly near the band-flip filling fraction because the band-flip filling fraction remains unaffected by the shifting. The independence of the band-flip filling fraction from lateral shifting is attributed to the superposition property of Bragg scattering processes in the asymmetric grating structure. Experimental verification in the terahertz range confirms significant control over the Q-factor of the leaky mode of the structure. The proposed asymmetric slab grating structure offers possibilities for mechanically controllable optical devices, which are applicable to tunable filters and sensors. This study advances our understanding and application of leaky modes in asymmetric grating structures, revealing a previously unexplored aspect of asymmetric optical lattice.
我们研究了一种非对称平板光栅结构，以在将频率变化降至最低的同时，实现对泄漏模式品质（Q）因子的显著调谐。该结构由放置在平板波导顶部和底部的两个相同光栅组成，其中一个光栅横向移位以引入不对称性。模拟表明，一个光栅的横向移位会在频率变化最小的情况下引起Q因子的广泛变化，特别是在带翻转填充分数附近，因为带翻转填充分数不受移位影响。带翻转填充分数与横向移位的独立性归因于非对称光栅结构中布拉格散射过程的叠加特性。太赫兹范围内的实验验证证实了对该结构泄漏模式Q因子的显著控制。所提出的非对称平板光栅结构为机械可控光学器件提供了可能性，这些器件适用于可调谐滤波器和传感器。这项研究推进了我们对非对称光栅结构中泄漏模式的理解和应用，揭示了非对称光学晶格以前未被探索的一个方面。
