近日，新加坡南洋理工大学的Baile Zhang及其研究小组与广东技术师范大学的Feng Wu合作并取得一项新进展。经过不懈努力，他们揭示太赫兹连续体中的准束缚态引发的突发侧向光束偏移。相关研究成果已于2025年1月9日在国际知名学术期刊《科学通报》上发表。

该研究团队通过实验证明，准连续体中的束缚态（QBICs）能够引发突发侧向光束偏移。通过对复合光栅波导应用布里渊区折叠技术，研究人员构建了一个QBIC带，其中所有状态均成为QBICs。当以特定入射角激发时，这些QBICs会产生突然的侧向光束偏移，而当频率偏离QBIC带时，这种偏移会迅速消失。

利用太赫兹成像技术，研究人员捕捉到了不同入射角下的光束偏移，从而对QBIC带进行了表征。这项工作为理解QBICs的行为提供了新的视角，并为先进传感器和波分（解）复用器的开发提供了支持。

据悉，连续体中的束缚态（BICs）在光子学领域因其无限大的品质因数（Q值）而著称。受扰动的BICs，或称准BICs（QBICs），具有有限但极高的Q值，从而允许外部耦合。迄今为止，大多数研究都集中在BICs和QBICs在动量空间的特性上，而关于它们在实空间的特性则讨论较少。

附：英文原文

Title: Abrupt lateral beam shifts from terahertz quasi-bound states in the continuum

Author: Minggui Wei , Yang Long , Feng Wu , Gui-Geng Liu , Baile Zhang

Issue&Volume: 2025/01/09

Abstract: Bound states in the continuum (BICs) are notable in photonics for their infinite Q factors. Perturbed BICs, or quasi-BICs (QBICs), have finite but ultra-high Q factors, enabling external coupling. So far, most studies have focused on the momentum-space properties of BICs and QBICs, with few discussions on their properties in real space. Here, we experimentally demonstrate that QBICs can induce abrupt lateral beam shifts. By applying Brillouin zone folding to a compound grating waveguide, we form a QBIC band where all states become QBICs. When excited at specific incident angles, these QBICs produce sudden lateral beam shifts, rapidly disappearing as frequencies deviate from the QBIC band. Using terahertz imaging, we capture these beam shifts at different incident angles, characterizing the QBIC band. This work offers alternative insights into QBIC behaviors and supports the development of advanced sensors and wavelength division (de) multiplexers.

DOI: 10.1016/j.scib.2025.01.006

Source: https://www.sciencedirect.com/science/article/pii/S2095927325000192