Nonlinear nonlocal metasurfaces

Abstract

Optical metasurfaces have recently emerged as the game changer in light manipulation and opened up new perspectives in many subfields of optics and photonics. Recent developments in nonlocal metasurfaces, in which the nanoscale building blocks respond to the incoming light collectively rather than as individual objects, are especially promising for enhancing and controlling the nonlinear optical phenomena. In this article, we provide a brief overview of the basic principles of nonlocal metasurfaces in the context of their nonlinear optical functionalities. We discuss the origin and the regimes of the nonlocal response, covering the aspects of multiple scattering, radiation damping, quality factor, local-field enhancement, and temporal dynamics. Some important aspects are illustrated by computational examples. We also give our personal viewpoint on the selected ideas and research directions in nonlocal and nonlinear metasurfaces, including the role of spatial symmetry in nonlocal interactions, the effects of phase and momentum matching in frequency conversion, as well as the possibilities offered by new material platforms and novel concepts, such as bound states in the continuum, parity–time symmetry, and time-variant metasurfaces.

Rayleigh anomaly induced phase gradients in finite nanoparticle chains

“…However, although these gradients can be probed by interferometric measurements, 60,61 their notable implication are the associated angular anomalies. Specifically, we show that the light reflected and diffracted from the chain deviates from the grating equation (eqn (8)) for infinite chains. Fig.…”

“…[1][2][3] It was shown that collectivity of the system may significantly enhance lightmatter interaction and support a plethora of attractive and highly tailorable physical phenomena. [1][2][3] For example, it can be beneficial for nonlinearity enhancement and manipulations, [4][5][6][7][8] induced transparency and slow light windows, [9][10][11] sensing, [12][13][14][15] lasing [16][17][18][19] and even for stimulating Bose-Einstein condensation at room temperature. 20 The theoretical analysis of periodic nanostructured systems usually requires the use of approximations that hide the full dynamics.…”

Temporal Dynamics of Collective Resonances in Periodic Metasurfaces

“…To illustrate our model, we assume E inc (t) to take the form of a Gaussian pulse, as in eq 3, with the central frequency ω = The impulse response function G(t) of a single resonance can be expressed as 26,121 = G t H t t ( ) ( )e sin( )…”

“…The theoretical IAC curve and the theoretical spectrogram were produced assuming the contribution of a single resonance with η = 0.2, Ω = 2.23 rad/fs (λ res ≈ 844.7 nm), and Γ = 0.005 rad/fs (Q factor ≈ 223). resonance, which hinders the coherent buildup of the local field amplitude, 26 producing only a moderate resonant TPEL enhancement. This fit-based analysis of IAC curves also provides quantitative insight in the multiresonant metasurfaces that show beat patterns in the IAC.…”

High-efficiency sum frequency generation from inverse designed metasurfaces

“…Recent advances in nanotechnologies have facilitated the development of ultra-thin single-layer dielectric metasurfaces, where optical nano-resonators can enhance and tailor the nonlinear interactions with functionalities beyond the capabilities of traditional bulky crystals [7]- [11]. To generate optical resonances, previous metasurface designs have often relied on semianalytical approaches in the limiting cases of Mietype modes for individual nanoresonators [12]- [18], or bound state in the continuum resonances [19]- [26]. The angular-dependent properties of nonlocal metasurfaces could also be utilized to tune the nonlinear interactions over a range of wavelengths [27].…”