We present a novel approach to designing high-quality bound states in the continuum (BIC) in dielectric metasurfaces using magnetic dipole resonances coupled to a mirror, enabling strong light–matter interaction without the need for asymmetric geometry or polarization dependence. This simplifies fabrication and enhances practical applications, demonstrated by a record-breaking third harmonic generation efficiency. Additionally, we showcase superior modulation characteristics with a pulsewidth-limited switching time of 100 fs and a remarkably low energy consumption, facilitated by the narrow photonic resonance of our metasurface. Our findings offer significant potential for optical sensing, quantum photonics, and nonlinear devices.
|