Large enhancement of the effective second-order nonlinearity in graphene metasurfaces

Using a powerful homogenization technique, one- and two-dimensional graphene metasurfaces are homogenized both at the fundamental frequency (FF) and second harmonic (SH). In both cases, there is excellent agreement between the predictions of the homogenization method and those based on rigorous numerical solutions of Maxwell equations. The homogenization technique is then employed to demonstrate that, owing to a double-resonant plasmon excitation mechanism that leads to strong, simultaneous field enhancement at the FF and SH, the effective second-order susceptibility of graphene metasurfaces can be enhanced by more than three orders of magnitude as compared to the intrinsic second-order susceptibility of a graphene sheet placed on the same substrate. In addition, we explore the implications of our results on the development of new active nanodevices that incorporate nanopatterned graphene structures.Comment: 11 pages, 12 figure

Nonlinear optical interactions of topological modes of photonic nanostructures

Topological photonics aims to utilize topological photonic bands and corresponding edge modes to implement robust light manipulation. Importantly, topological photonics provide an ideal platform to study nonlinear interactions. In this talk, I will review some recent results regarding nonlinear interactions of one-way edge-modes in frequency mixing processes in topological photonic nanostructures. More specifically, I will discuss the band topology of 2D photonic crystals with hexagonal symmetry and demonstrate that SHG and THG can be implemented via one-way edge modes. Moreover, I will demonstrate that more exotic phenomena, such as slow-light enhancement of nonlinear interactions and harmonic generation upon interaction of backward-propagating edge modes can also be realized. Finally, FWM of topological plasmon modes of graphene plasmonic crystals and SHG upon interaction of valley-Hall topological modes of all-dielectric photonic crystals will be discussed

Comparison Between the Linear and Nonlinear Homogenization of Graphene and Silicon Metasurfaces

In this article, we use a versatile homogenization approach to model the linear and nonlinear optical response of two metasurfaces: a plasmonic metasurface consisting of graphene patches and a dielectric photonic nanostructure consisting of silicon photonic crystal (PhC) cavities. The former metasurface is resonant at wavelengths that are much larger than the graphene elements of the metasurface, whereas the resonance wavelengths of the latter one are comparable to the size of its resonant components. By computing and comparing the effective permittivities and nonlinear susceptibilities of the two metasurfaces, we infer some general principles regarding the conditions under which homogenization methods of metallic and dielectric metasurfaces are valid. In particular, we show that in the case of the graphene metasurface the homogenization method describes very well both its linear and nonlinear optical properties, whereas in the case of the silicon photonic nanostructure the homogenization method is only qualitatively accurate, especially near the optical resonances

Dark-Soliton Timing Jitter Caused By Fluctuations In Initial Pulse-Shape

The dark-soliton timing jitters caused by fluctuations in either the soliton initial phase angle or the background amplitude when such a soliton propagates in a monomode optical fiber under the influence of the stimulated Raman scattering are investigated and compared with those that exist when the stimulated Raman scattering is not present. In addition, it is demonstrated that in the presence of the stimulated Raman scattering, there exists a distance at which, for the negative soliton initial phase angle, the dark-soliton timing jitter caused by fluctuations in the background amplitude becomes zero

Interaction of pulses in nonlinear Schroedinger model

The interaction of two rectangular pulses in nonlinear Schroedinger model is studied by solving the appropriate Zakharov-Shabat system. It is shown that two real pulses may result in appearance of moving solitons. Different limiting cases, such as a single pulse with a phase jump, a single chirped pulse, in-phase and out-of-phase pulses, and pulses with frequency separation, are analyzed. The thresholds of creation of new solitons and multi-soliton states are found.Comment: 9 pages, 7 figures. Accepted to Phys. Rev. E, 200

Fano resonance resulting from a tunable interaction between molecular vibrational modes and a double-continuum of a plasmonic metamolecule

Coupling between tuneable broadband modes of an array of plasmonic metamolecules and a vibrational mode of carbonyl bond of poly(methyl methacrylate) is shown experimentally to produce a Fano resonance, which can be tuned in situ by varying the polarization of incident light. The interaction between the plasmon modes and the molecular resonance is investigated using both rigorous electromagnetic calculations and a quantum mechanical model describing the quantum interference between a discrete state and two continua. The predictions of the quantum mechanical model are in good agreement with the experimental data and provide an intuitive interpretation, at the quantum level, of the plasmon-molecule coupling

Negative Refraction and Left-handed electromagnetism in Microwave Photonic Crystals

We demonstrate negative refraction of microwaves in metallic photonic crystals. The spectral response of the photonic crystal, which manifests both positive and negative refraction, is in complete agreement with band-structure calculations and numerical simulations. The negative refraction observed corresponds to left-handed electromagnetism and arises due to the dispersion characteristics of waves in a periodic medium. This mechanism for negative refraction is different from that in metamaterials.Comment: 13 pages, 4 figure

Achieving sub-diffraction imaging through bound surface states in negative-refracting photonic crystals at the near-infrared

We report the observation of imaging beyond the diffraction limit due to bound surface states in negative refraction photonic crystals. We achieve an effective negative index figure-of-merit [-Re(n)/Im(n)] of at least 380, ~125x improvement over recent efforts in the near-infrared, with a 0.4 THz bandwidth. Supported by numerical and theoretical analyses, the observed near-field resolution is 0.47 lambda, clearly smaller than the diffraction limit of 0.61 lambda. Importantly, we show this sub-diffraction imaging is due to the resonant excitation of surface slab modes, allowing refocusing of non-propagating evanescent waves