An actively ultrafast tunable giant slow-light effect in ultrathin nonlinear metasurfaces

Abstract

A slow-light effect based on metamaterial-induced transparency (MIT) possesses great practical applications for integrated photonic devices. However, to date, only very weak slow-light effects have been obtained in metamaterials because of the intrinsic loss of metal. Moreover, no active control of slow-light has been achieved in metamaterials. Here, we report the realization of a giant slow-light effect on an ultrathin metasurface that consists of periodic arrays of gold nanoprism dimers with a thickness of 40 nm sandwiched between a multilayer-graphene micro-sheet/zinc oxide nanoparticle layer and a monolayer graphene/polycrystalline indium tin oxide layer. The strong field confinement of the plasmonic modes associated with the MIT ensures a tremendous reduction in the group velocity around the transparency window. A group index of more than 4 3 10 3 is achieved, which is one order of magnitude greater than that of previous reports. A large tunable wavelength range of 120 nm is achieved around the center of the transparency window when the pump light intensity is only 1.5 kW cm 22 . The response time is as fast as 42.3 ps. These results demonstrate the potential for the realization of various functional integrated photonic devices based on metasurfaces, such as all-optical buffers and all-optical switches. INTRODUCTIONThe slow-light effect plays an essential role in the field of nonlinear optics. Typical materials that have been used to achieve the slow-light effect include photonic crystals, optical fibers, and optical microcavities. [1][2][3][4][5] Recently, the slow-light effect has been realized based on metamaterial-induced transparency (MIT). 6-11 However, only a small group index of 100 was obtained in photonic metamaterials because of the relatively large intrinsic loss of metal. 6-11 Moreover, various functional integrated photonic devices, including ultrafast all-optical buffers and all-optical switches, require ultrafast control of the slow-light effect. Photonic metasurfaces offer a variety of opportunities to control light using flat and surface components and have attracted wide attention for their great practical applications in the field, such as optical computing, optical communications, and integrated photonic circuits. [12][13][14][15][16][17] To date, no ultrafast active control of the slow-light effect in metamaterials has been reported.In this letter, we report the realization of an ultrafast all-optical tunable giant slow-light effect in an ultrathin metasurface. The metasurface consists of periodic arrays of gold nanoprism dimers sandwiched between a multilayer-graphene micro-sheet/zinc oxide (ZnO) nanoparticle layer and a monolayer graphene/polycrystalline indium tin oxide (ITO) layer. The strong field confinement of the plasmonic modes associated with the MIT ensures a large reduction in the group velocity in the transparency window. The enhanced nonlinearity brought about by the quantum confinement (QC) effect provided by the ZnO nanoparticles and polycrystalline ITO nanograins, hot...

Surface Lattice Resonances in THz Metamaterials

“…Within the transparency window, light experiences an anomalous phase change because of a steep dispersion. The induced steep dispersion of the medium can slow the propagation of light pulses by several orders of magnitude [41,[81][82][83] and enhances nonlinear interactions [84]. Such narrow and highly dispersive transparency windows possess a high Q-factor and are a promising platform for sensing and nonlinear applications.…”

Dispersion of 20 fs pulses through band edges of cholesteric liquid crystals

“…The phase φ(ω) is usually written as : where ω 0 is the central frequency of the pulse. The first four terms are well-known and respectively refer to : the carrier-to-envelope phase (φ (0) ), the group delay (φ (1) ), the chirp or group delay dispersion (GDD, φ (2) ), and third-order dispersion (TOD, φ (3) ). Addressing φ (0) and φ (1) with nematic LC layers was covered in [17].…”

“…Optical dispersion engineering in a material medium triggers advanced light manipulation capabilities, such as slow and fast light, group delay steering and ultrafast pulse shaping. Some examples of these advanced media include photonic crystals [1], photorefractive crystals [2] or metasurfaces [3,4]. Photonic structures, in particular, are well-known to enable light group velocity dispersion control in the vicinity of the spectral bandgap [5].…”

Graphene Plasmonics: A Platform for 2D Optics

“…Metamaterials, [60][61][62][63][64][65][66][67][68][69][70][71][72][73] formed by tailored subwavelength building blocks, serve as a promising platform for versatile manipulation of light by exploiting the excitations of plasmonic resonances and Mie resonances. Metamaterials made of a single or a few planar layers, named as metasurfaces, [74][75][76][77][78][79][80][81] have attracted particular interests in light manipulation.…”