Nonlinear Metasurfaces Governed by Bound States in the Continuum
journal contributionposted on 25.06.2019, 00:00 by Kirill Koshelev, Yutao Tang, Kingfai Li, Duk-Yong Choi, Guixin Li, Yuri Kivshar
Nonlinear nanostructured surfaces provide a paradigm shift in nonlinear optics with new ways to control and manipulate frequency conversion processes at the nanoscale, also offering novel opportunities for applications in photonics, chemistry, material science, and biosensing. Here, we develop a general approach to employ sharp resonances in metasurfaces originated from the physics of bound states in the continuum for both engineering and enhancing the nonlinear response. We study experimentally the third-harmonic generation from metasurfaces composed of symmetry-broken silicon meta-atoms and reveal that the harmonic generation intensity depends critically on the asymmetry parameter. We employ the concept of the critical coupling of light to the metasurface resonances to uncover the effect of radiative and nonradiative losses on the nonlinear conversion efficiency.
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nonradiative lossesnonlinear conversion efficiencyparadigm shiftthird-harmonic generationfrequency conversion processessymmetry-broken silicon meta-atomsgeneration intensitynonlinear responseBound Statesmetasurface resonancesnonlinear opticsasymmetry parameterContinuum Nonlinear nanostructured surfacesNonlinear Metasurfacesmaterial scienceoffering novel opportunities