Physics

Resonance (particle physics)

Nonlinear system

Dipole

Bound state

Second-harmonic generation

Nanoscopic scale

Laser

Nonlinear optics

Resonator

Optics

Dielectric

Condensed matter physics

Quantum mechanics

High harmonic generation

Optoelectronics

Physical Review Letters

Being motivated by the recent prediction of high-$Q$ modes in subwavelength dielectric resonators inspired by bound states in the continuum (BIC), we study the second-harmonic generation from isolated subwavelength AlGaAs nanoantennas. We reveal that nonlinear effects at the nanoscale can be enhanced dramatically provided the resonator parameters are tuned to the BIC regime. We predict a record-high conversion efficiency for nanoscale resonators that exceeds by 2 orders of magnitude the conversion efficiency observed at the magnetic dipole Mie resonance, thus opening the way for highly efficient nonlinear metasurfaces and metadevices.

Giant Nonlinear Response at the Nanoscale Driven by Bound States in the Continuum