53 research outputs found
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
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
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
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
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
Semi-discrete solitons in arrayed waveguide structures with Kerr nonlinearity
We construct families of optical semi-discrete composite solitons (SDCSs),
with one or two independent propagation constants, supported by a planar slab
waveguide, XPM-coupled to a periodic array of stripes. Both structures feature
the cubic nonlinearity and support intrinsic modes with mutually orthogonal
polarizations. We report three species of SDCSs, odd, even, and twisted ones,
the first type being stable. Transverse motion of phase-tilted solitons, with
potential applications to beam steering, is considered too.Comment: 6 pages, 9 figure
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