Phys.org March 22, 2024
A boundary mode localized on one side of a finite-size lattice can tunnel to the opposite side which results in unwanted couplings and the tunneling probability decays exponentially with the size of the system which requires many lattice sites before eventually becoming negligibly small. An international team of researchers (USA – PNNL, China) showed that the tunneling probability for some boundary modes can apparently vanish at specific wavevectors and a boundary mode can be completely trapped within very few lattice sites where the bulk bandgap is not even well-defined. The number of trapped states equaled the number of lattice sites along the normal direction of the boundary. They provided two configurations and validated the existence of this peculiar finite barrier-bound state experimentally in a dielectric photonic crystal at microwave frequencies. According to the researchers their work offers extreme flexibility in tuning the coupling between localized states and channels as well as a new mechanism that facilitates unprecedented manipulation of light… read more. Open Access TECHNICAL ARTICLE
Illustration of bound state in the continuum… Credit: Light: Science & Applications volume 13, Article number: 69 (2024)