Sun Changlin, Liu Haiyi, Qi Pengfei, Zhu Liguo, Guo Lanjun, Lin Lie, Liu Weiwei
Institute of Modern Optics, Nankai University, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology, Tianjin 300350, China.
National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang, Sichuan 621900, China.
Nanoscale. 2023 Aug 10;15(31):12907-12914. doi: 10.1039/d3nr01670f.
Deep-subwavelength features have a minimal impact on wave transport in all dielectric systems; thus the homogenization approach was commonly adopted. Recently, the breakdown of effective medium theory (EMT) for the incident wave near the total reflection (TR) angle was demonstrated in a deep-subwavelength dielectric multilayer. Additionally, anomalous transmission was reported at angles exceeding the TR angle when introducing disorder and was attributed to Anderson localization. Here we firstly demonstrated that the alleged anomalous transmission also occurs in the disorder-free case, illustrating that attributing anomalous transmission to Anderson localization deserves a more in-depth study. To clarify the underlying physics of this asserted anomalous transmission, Anderson localization and broken EMT, the incident angle dependent reflectivity and modes for ordered and disordered deep-subwavelength multilayers were investigated systematically. Actually, the EMT is still convincing and the anomalous transmission is reasonable after a simple correction. However, the anomalous transmission is more accessible and the permittivity correction is more imperative in the disordered system due to the Anderson localization. These findings can be expanded to other wave systems such as acoustic waves and matter waves, providing insight into EMT and deepening our understanding of the intriguing transport phenomena in deep subwavelength systems.
深亚波长特征对所有介电系统中的波传输影响极小；因此，均匀化方法被普遍采用。最近，在深亚波长介电多层膜中证明了有效介质理论（EMT）对于接近全反射（TR）角的入射波的失效。此外，当引入无序时，在超过TR角的角度处报道了异常透射，并归因于安德森局域化。在此，我们首先证明了所谓的异常透射在无无序情况下也会发生，这表明将异常透射归因于安德森局域化值得更深入的研究。为了阐明这种声称的异常透射、安德森局域化和失效的EMT的潜在物理机制，系统地研究了有序和无序深亚波长多层膜的入射角相关反射率和模式。实际上，经过简单修正后，EMT仍然令人信服，并且异常透射是合理的。然而，由于安德森局域化，在无序系统中异常透射更容易出现，介电常数修正也更为迫切。这些发现可以扩展到其他波系统，如声波和物质波，为EMT提供见解，并加深我们对深亚波长系统中有趣传输现象的理解。
