Ultrathin Second‐Harmonic Metasurfaces with Record‐High Nonlinear Optical Response

Lee, Jongwon; Nookala, Nishant; Gómez‐Díaz, J. S.; Tymchenko, Mykhailo; Demmerle, Frederic; Boehm, Gerhard; Amann, Markus; Alù, Andrea; Belkin, Mikhail

doi:10.1002/adom.201500723

Cited by 94 publications

(98 citation statements)

References 29 publications

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“…Furthermore, deeply subwavelength (∼ λ/20) metal-semiconductor nanocavities were introduced, which not only convert z-polarized MQW nonlinear susceptibility into the transverse plane but provide further enhancement to the nonlinear response [356,357]. Combined with innovations in the MQW design, this approach allowed to produce a record-high secondorder nonlinear optical response of 1.2 × 10 6 pm V −1 at λ = 10 µm, which is about 3−5 orders of magnitude higher than that of traditional nonlinear materials and nonlinear plasmonic metasurfaces, and the experimentally achieved absolute conversion efficiency is up to 0.075% using pumping intensities of only 15 kW cm −2 [356]. It should be noted although the effective nonlinear susceptibility is significantly enhanced by orders of magnitude compared to traditional nonlinear materials; the absolute conversion efficiency is still low.…”

Section: Nonlinear Metasurfacesmentioning

confidence: 99%

Gradient metasurfaces: a review of fundamentals and applications

2017

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In the wake of intense research on metamaterials the two-dimensional analogue, known as metasurfaces, has attracted progressively increasing attention in recent years due to the ease of fabrication and smaller insertion losses, while enabling an unprecedented control over spatial distributions of transmitted and reflected optical fields. Metasurfaces represent optically thin planar arrays of resonant subwavelength elements that can be arranged in a strictly or quasi periodic fashion, or even in an aperiodic manner, depending on targeted optical wavefronts to be molded with their help. This paper reviews a broad subclass of metasurfaces, viz. gradient metasurfaces, which are devised to exhibit spatially varying optical responses resulting in spatially varying amplitudes, phases and polarizations of scattered fields. Starting with introducing the concept of gradient metasurfaces, we present classification of different metasurfaces from the viewpoint of their responses, differentiating electricaldipole, geometric, reflective and Huygens' metasurfaces. The fundamental building blocks essential for the realization of metasurfaces are then discussed in order to elucidate the underlying physics of various physical realizations of both plasmonic and purely dielectric metasurfaces. We then overview the main applications of gradient metasurfaces, including waveplates, flat lenses, spiral phase plates, broadband absorbers, color printing, holograms, polarimeters and surface wave couplers. The review is terminated with a short section on recently developed nonlinear metasurfaces, followed by the outlook presenting our view on possible future developments and perspectives for future applications.

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Section: Nonlinear Metasurfacesmentioning

confidence: 99%

Gradient metasurfaces: a review of fundamentals and applications

2017

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“…factor Q ef f reaches its maximum value ∼ 5 ω ν 2γ 21 . For smaller values of Γ r the intracavity quantum efficiency will stay roughly the same, limited by the dissipation rate γ 21 of the optical polarization, whereas the radiation power outcoupled from the cavity reduces ∝ Γ r .…”

Section: Spontaneous Emission From An Ensemble Of Nonequilibrium Fmentioning

confidence: 95%

“…For a fixed transition linewidth γ 21 we normalize Q ef f by the Q-factor of the radiative transition ω 21 2γ 21 and plot the normalized Q-factor Q norm = 2γ 21 ∆ω ef f as a function of the cavity linewidth Γ r ; see Fig. 2.…”

Section: Spontaneous Emission From An Ensemble Of Nonequilibrium Fmentioning

confidence: 99%

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Enhancement of the spontaneous emission in subwavelength quasi-two-dimensional waveguides and resonators

et al. 2018

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We consider a quantum-electrodynamic problem of the spontaneous emission from a twodimensional (2D) emitter, such as a quantum well or a 2D semiconductor, placed in a quasi-2D waveguide or cavity with subwavelength confinement in one direction. We apply the Heisenberg-Langevin approach which includes dissipation and fluctuations in the electron ensemble and in the electromagnetic field of a cavity on equal footing. The Langevin noise operators that we introduce do not depend on any particular model of dissipative reservoir and can be applied to any dissipation mechanism. Moreover, our approach is applicable to nonequilibrium electron systems, e.g. in the presence of pumping, beyond the applicability of the standard fluctuation-dissipation theorem. We derive analytic results for simple but practically important geometries: strip lines and rectangular cavities. Our results show that a significant enhancement of the spontaneous emission, by a factor of order 100 or higher, is possible for quantum wells and other 2D emitters in a subwavelength cavity.

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“…Metamaterial, a type of artificial material allowing unprecedented control of light and exhibiting intriguing optical properties not found in nature [8][9][10][11], may offer an opportunity of realizing custom-design nonlinear properties. Various approaches were reported to introduce the nonlinearity to metamaterials, for example, engineering metaatoms with nonlinear insertions, such as varactor diodes [12,13]; structuring metamaterials with metal films, whose nonlinearity arises from the surface contribution [14,15]; and combining conventional nonlinear materials as host media, such as quantum wells [16,17]. With these methods, rapid progress on optical nonlinearity in metamaterials has been reported, including phase mismatch-free [18], electrical control [19,20], and giant nonlinear susceptibility [21,22].…”

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confidence: 99%

Artificial Nonlinearity Generated from Electromagnetic Coupling Metamolecule

Wen

Zhou

2017

Phys. Rev. Lett.

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A purely artificial mechanism for optical nonlinearity is proposed based on a metamaterial route. The mechanism is derived from classical electromagnetic interaction in a meta-molecule consisting of a cut-wire meta-atom nested within a splitring meta-atom. Induced by the localized magnetic field in the split-ring meta-atom, the magnetic force drives an anharmonic oscillation of free electrons in the cut-wire metaatom, generating an intrinsically nonlinear electromagnetic response. An explicit physical process of a second-order nonlinear behavior is adequately described, which is perfectly demonstrated with a series of numerical simulations. Instead of "borrowing" from natural nonlinear materials, this novel mechanism of optical nonlinearity is artificially dominated by the meta-molecule geometry and possesses unprecedented design freedom, offering fascinating possibilities to the research and application of nonlinear optics.Nonlinear optics has become thriving since the first observation of the second harmonic generation (SHG) in 1961 [1], and plays an essential role in many optical devices such as frequency up-converters and mixers, nonlinear spectrometers, and new light sources [2]. Over the past half century, with tons of efforts focused on searching new nonlinear materials [3, 4], researchers endeavor to uncover the physical mechanism behind the optical nonlinearity [5]. As a universal phenomenon, nonlinearity is exhibited by almost all materials interacting with sufficiently strong light [6], and various fundamental mechanisms were proposed, such as distortion of the electron cloud, relative motion of nuclei, reorientation of molecules, electrostriction effect, and thermal effect [7]. Despite the fact that these phenomenological theories extensively advanced the development of new nonlinear materials in the past several decades, they

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Ultrathin Second‐Harmonic Metasurfaces with Record‐High Nonlinear Optical Response

Cited by 94 publications

References 29 publications

Gradient metasurfaces: a review of fundamentals and applications

Gradient metasurfaces: a review of fundamentals and applications

Enhancement of the spontaneous emission in subwavelength quasi-two-dimensional waveguides and resonators

Artificial Nonlinearity Generated from Electromagnetic Coupling Metamolecule

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