Aigner Andreas, Ligmajer Filip, Rovenská Katarína, Holobrádek Jakub, Idesová Beáta, Maier Stefan A, Tittl Andreas, de S Menezes Leonardo
Chair in Hybrid Nanosystems, Nano-Institute Munich, Faculty of Physics, Ludwig-Maximilians-University Munich, Munich 80539, Germany.
Central European Institute of Technology, Brno University of Technology, 61200 Brno, Czech Republic.
Nano Lett. 2024 Sep 4;24(35):10742-10749. doi: 10.1021/acs.nanolett.4c01703. Epub 2024 Aug 27.
Active functionalities of metasurfaces are of growing interest in nanophotonics. The main strategy employed to date is spectral resonance tuning affecting predominantly the far-field response. However, this barely influences other essential resonance properties like near-field enhancement, signal modulation, quality factor, and absorbance, which are all vital for numerous applications. Here we introduce an active metasurface approach that combines temperature-tunable losses in vanadium dioxide with far-field coupling tunable symmetry-protected bound states in the continuum. This method enables exceptional precision in independently controlling both radiative and nonradiative losses. Consequently, it allows for the adjustment of both the far-field response and, notably, the near-field characteristics like local field enhancement and absorbance. We experimentally demonstrate continuous tuning from under- through critical- to overcoupling, achieving quality factors of 200 and a relative switching contrast of 78%. Our research marks a significant step toward highly tunable metasurfaces, controlling both near- and far-field properties.
超表面的有源功能在纳米光子学中越来越受到关注。迄今为止采用的主要策略是光谱共振调谐，主要影响远场响应。然而，这几乎不会影响其他重要的共振特性，如近场增强、信号调制、品质因数和吸光度，而这些特性对于众多应用来说都是至关重要的。在此，我们介绍一种有源超表面方法，该方法将二氧化钒中温度可调的损耗与连续统中受对称性保护的远场耦合可调束缚态相结合。这种方法能够在独立控制辐射损耗和非辐射损耗方面实现极高的精度。因此，它不仅可以调节远场响应，还能显著调节近场特性，如局部场增强和吸光度。我们通过实验证明了从欠耦合到临界耦合再到过耦合的连续调谐，实现了200的品质因数和78%的相对开关对比度。我们的研究朝着高度可调谐超表面迈出了重要一步，可同时控制近场和远场特性。
