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

太赫兹准连续域束缚态诱导的侧向光束位移突变

作　　者：Minggui Wei Yang Long Feng Wu Gui-Geng Liu Baile Zhang 魏明贵;龙洋;吴丰;刘癸庚;张柏乐

机构地区：[1]Division of Physics and Applied Physics,School of Physical and Mathematical Sciences,Nanyang Technological University,Singapore 637371,Singapore [2]School of Optoelectronic Engineering,Guangdong Polytechnic Normal University,Guangzhou 510665,China [3]Centre for Disruptive Photonic Technologies,The Photonics Institute,Nanyang Technological University,Singapore 639798,Singapore

出　　处：《Science Bulletin》2025年第6期882-888,共7页科学通报(英文版)

基　　金：supported by the Singapore National Research Foundation Competitive Research Program(NRF-CRP23-2019-0007);the Singapore Ministry of Education Academic Research Fund Tier 2(MOE-T2EP50123-0007);Feng Wu acknowledges support from the National Natural Science Foundation of China(12104105);Guangdong Basic and Applied Basic Research Foundation(2023A1515011024).

摘　　要：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.

关 键 词：Bound states in the continuum Lateral shifts Terahertz optics 

分 类 号：O43[机械工程—光学工程]