Nonlinear response from optical bound states in the continuum

Abstract

We consider nonlinear effects in scattering of light by a periodic structure supporting optical bound states in the continuum. In the spectral vicinity of the bound states the scattered electromagnetic field is resonantly enhanced triggering optical bistability. Using coupled mode approach we derive a nonlinear equation for the amplitude of the resonant mode associated with the bound state. We show that such an equation for the isolated resonance can be easily solved yielding bistable solutions which are in quantitative agreement with the full-wave solutions of Maxwell’s equations. The coupled mode approach allowed us to cast the the problem into the form of a driven nonlinear oscillator and analyze the onset of bistability under variation of the incident wave. The results presented drastically simplify the analysis nonlinear Maxwell’s equations and, thus, can be instrumental in engineering optical response via bound states in the continuum.

Exploring the Optical Bound State in the Continuum in a Dielectric Grating Coupled Plasmonic Hybrid System

“…Since the selected dielectric medium possesses a high nonlinear coefficient, the extraordinary confinement of optical energy within the medium can offer interesting nonlinear optical processes. [36,58,59] Therefore, improved Q-factor with high field confinement in the nonlinear chalcogenide medium can provide the unique possibility of engineering the nonlinear optical process such as absorption, harmonic generation, selffocusing, and bistability. Apart from it, the better Q-factor of the resonance dip also can demonstrate sensing applications.…”

“…[ 34 ] The nonlinear dynamics in the trapped states have also been investigated for enhanced nonlinear processes. [ 35,36 ] In a photonic crystal slab with Kerr medium, the formation of BIC demonstrated strong nonlinear interaction at a low pump power even without a cavity. [ 37 ] Considering the quasi‐BIC conditions in a meta‐surface, a super cavity has been constructed for obtaining a high Q‐factor, which demonstrates huge nonlinear enhancement toward the second harmonic generation.…”

Fano feature induced by a bound state in the continuum via resonant state expansion

“…We believe that the results presented offer a new angle onto the resonant state expansion method paving a way to analytic treatment of resonant scattering due to optical BICs. In particular we expect that the resonant approximation can be invoked to build a rigorous theory of nonlinear response 55 . Recently, the Fano resonance induced by an optical BIC in a liquid crystal ADL has been reported experimentally in 56 at the Brewster angle.…”

Ridge Resonance in Silicon Photonics Harnessing Bound States in the Continuum

“…Due to the single resonance over a broad wavelength range, this shift can be unambiguously detected unlike other types of resonators that exhibits multiple resonances with small free spectral ranges, resulting in increasing sensing dynamic range. Strong evanescent field is also attractive for strong light–matter coupling and nonlinear optic interaction in BIC's …”