Quasi-bound states in the continuum with a stable resonance wavelength in dimer dielectric metasurfaces

Abstract Symmetry-protected bound states in the continuum (SP-BICs) are one of most intensively studied BICs. Typically, SP-BICs must be converted into quasi-BICs (QBICs) by breaking unit cell’s symmetry so that they can accessed external excitation. The symmetry-broken usually results a varied resonance wavelength QBICs which also highly sensitive to asymmetry parameters. In this work, we demonstrate with stable realized translational an all-dielectric metasurface. cell metasurface is made silicon nanodisk dimer. Q-factor precisely tuned changing interspacing two nanodisks while their quite against interspacing. We find such BICs show weak dependence on shape nanodisk. Multiple decompositions indicate toroidal dipole dominates type QBIC. wavelengths only either lattice constants or radius Finally, present experimental demonstrations QBIC wavelength. highest measured >3000. Our may promising applications enhancing light–matter interaction.