Electrifying photonic metamaterials for tunable nonlinear optics

Abstract

Metamaterials have not only enabled unprecedented flexibility in producing unconventional optical properties that are not found in nature, they have also provided exciting potential to create customized nonlinear media with high-order properties correlated to linear behaviour. Two particularly compelling directions are active metamaterials, whose optical properties can be purposely tailored by external stimuli in a reversible manner, and nonlinear metamaterials, which enable intensity-dependent frequency conversion of light waves. Here, by exploring the interaction of these two directions, we leverage the electrical and optical functions simultaneously supported in nanostructured metals and demonstrate electrically controlled nonlinear optical processes from a metamaterial. Both second harmonic generation and optical rectification, enhanced by the resonance behaviour in the metamaterial absorber, are modulated externally with applied voltage signals. Our results reveal an opportunity to exploit optical metamaterials as self-contained, dynamic electro-optic systems with intrinsically embedded electrical functions and optical nonlinearities.

Backward phase-matching for nonlinear optical generation in negative-index materials

“…3a. Instead of the regular χ (2) response intrinsic to non-centrosymmetric crystals and interfaces, here the effective second-order nonlinear effect is produced by the interplay between the ubiquitous third-order nonlinear susceptibility χ (3) and the applied control field (χ (3) E C → χ (2) eff ; refs [36][37][38]. Moreover, the 30-nm-thick dielectric spacer is split into two halves, 15 nm each, made of Si 3 N 4 and HfO 2 (Fig.…”

Hybrid metamaterials for electrically triggered multifunctional control

“…However, a close inspection of these studies reveals that the observed transition is extremely localized and hinges on electrical current filaments, suggesting that this direct electrically induced transition may not be sufficient to enable detectable modulations in metamaterials. Recently, nano-engineered metals have been comprehensively used in metamaterial and plasmonic systems, because in addition to facilitating optical resonances their electrical conductivities enable complex functionalities for achieving plasmonic-enhanced electro-optic effects in both the linear and nonlinear regimes414243. Metadevices with intrinsically embedded electrical and optical functions are correspondingly referred to as ‘self-sufficient' or ‘self-contained'.…”

Bifacial Metasurface with Quadrupole Optical Response

“…As an example, a metamaterial can be designed to have a negative refractive index in order to provide "perfect imaging" [3][4][5][6][7] and simultaneously the impedance equal to that of vacuum in order to minimize optical reflection from the material's surface. Other extraordinary applications include optical cloaking devices [8,9], elements enhancing optical density of states and energy transfer [10,11] as well as coherence [12][13][14], and a variety of optical elements composed of dispersive and nonlinear materials [15][16][17].…”