Mechanically induced dynamic QBIC-BIC switching and sensing performance enhancement using elastomer-based double resonant gratings

A quasi-bound state in the continuum (QBIC) is a hot topic in optics, as it brings extremely high Q factors by slightly breaking the structural symmetry or tuning geometric parameters. However, QBIC devices are usually not dynamically tunable; thus, achieving this ultra-high Q factor demands ultra-high fabrication accuracy. Here, by first proposing an elastomer-based double resonant gratings (DRG) in the THz band, a strategy to realize dynamically tunable QBIC devices is presented. By simple stretching, structural parameters can be tuned, leading to dynamic QBIC-BIC switching, dynamic Q factors tuning to the order of 10 6 , and enhancement of sensing performance. Moreover, by varying the incident angle, this dynamic tuning is achievable at a constant frequency. The strategy is expected to neutralize the demanding requirements for fabrication accuracy in the implementation of QBIC devices. Hence, it is a promising solution to realize tunable QBIC devices for applications such as THz biosensing.