Hyperbolic carbon nanoforest for phase matching of ordinary and backward electromagnetic waves: second harmonic generation

We show that deliberately engineered dispersive metamaterial slab can enable the co-existence and phase matching of contra-propagating ordinary fundamental and extraordinary backward second harmonic surface electromagnetic modes. Energy flux and phase velocity are contra-directed in the backward waves which is the phenomenon that gives rise to unique nonlinear optical propagation processes. We show that frequencies, phase, and group velocities, as well as nanowaveguide losses inherent to the electromagnetic modes supported by such metamaterial, can be tailored to maximize conversion of frequencies and to reverse propagation direction of the generated wave. Such a possibility, which is of paramount importance for nonlinear photonics, is proved with a numerical model of the hyperbolic metamaterial made of carbon nanotubes standing on the metal surface. Extraordinary properties of the backward-wave second harmonic generation in the reflection direction and of the corresponding frequency doubling metareflector in the THz are investigated with a focus on the pulsed regime.Comment: 6 pages, 5 figures. arXiv admin note: text overlap with arXiv:1602.0249

Lateral radiative forces exerted by evanescent fields along a hyperbolic metamaterial slab

We show and investigate the optical forces acting on a particle in the vicinity of a planar waveguide which is lled with hyperbolic material and supports propagation across its plane (two-dimensional). The anisotropy axis of its medium lies in plane of the waveguide. In contrast to commonly considered pushing or pulling forces, acting in one-dimensional guiding structures, in the case of two-dimensional wave propagation, the angles between the momentum and the total energy ow may take any value around the circle. Accordingly, evanescent elds out of the slab exert lateral radiative forces on a nanoparticle oriented parallel to momentum being controllably di erent from the total energy ow direction. This provides a exibility in manipulation by nanoparticles by employing suitably engineered hyperbolic structures

Waveguide containing a backward-wave slab

We have considered theoretically the waveguide properties of a plane two-layered waveguide, whose one layer is a usual magnetodielectric (forward-wave medium), but another one is a slab of so-called backward-wave material (BW-material), whose both permittivity and permeability are negative. We have analyzed the properties of eigenwaves in this waveguide. In particular, it was found that there exist waves of both TE and TM polarizations, whose fields decay exponentially from the interface of the two slabs inside both layers, and their slow-wave factor tends to infinity at small frequencies. Thus, this waveguiding system supports super-slow waves with extremely short wavelengthes, as compared to the free-space wavelength and the cross section size. Other peculiarities of the spectrum are also discussed