We investigate the modulational instability of plane waves in quadratic nonlinear materials with linear and nonlinear quasi-phase-matching gratings. Exact Floquet calculations, confirmed by numerical simulations, show that the periodicity can drastically alter the gain spectrum but never completely removes the instability. The low-frequency part of the gain spectrum is accurately predicted by a...

We present computer simulation data for the effective permittivity ~in the quasistatic limit! of a system composed of discrete inhomogeneities of permittivity e1 , embedded in a three-dimensional homogeneous matrix of permittivity e2 . The primary purpose of this paper is to study the related issue of the effect of the geometric shape of the components on the dielectric properties of the medium...

There is an increasing interest in the study of metamaterials and periodic materials across disciplines. These are anisotropic their properties present directionality. For example, wave speed depends on propagation direction. Furthermore, they heterogeneous, directionality spectra. Common approaches to describe anisotropy have been used large-wavelength approximation corresponding static proper...

We fabricated sub-wavelength periodic structures by thermal nano-imprinting using our original functionally modified inorganic–organic hybrid materials. The fabricated structures exhibited excellent uniformity and surface smoothness over a large imprinted area. In addition, optical transmittance is more than 90% within visible wavelength regions after heat treatment for 2 h at 300 C. These nano...

The variational asymptotic method for unit cell homogenization is used to find the sensitivity of the effective properties of periodically heterogeneous materials, within a periodic base-cell. The sensitivities are found by the direct differentiation of the variational asymptotic method for unit cell homogenization (VAMUCH) and by the method of adjoint variables. This sensitivity theory is impl...