In this paper, we have systematically investigated light propagating in the hyperbolic metamaterials (HMMs) covered by a subwavelength grating. Based on the equal-frequency contour analyses, light in the HMM is predicted to propagate along a defined direction because of its hyperbolic dispersion, which is similar to the self-collimating effects in photonic crystals. By using the finite-difference time-domain, numerical simulations demonstrate a subwavelength bright spot at the intersection of the adjacent directional beams. Different from the images in homogeneous media, the magnetic fields and electric fields at the spot are layered, especially for the electric fields Ez that is polarized to the propagating direction, i.e., the layer normal direction. Moreover, the Ez is hollow in the layer plane and is stronger than the other electric field component Ex. Therefore, the whole electric field is structured and its pattern can be tuned by the HMM’s effective anisotropic electromagnetic parameters. Our results may be useful for generating subwavelength structured light.
We have investigated the effective electromagnetic parameters of a two-dimensional photonic crystal even though the
wavelength is on the order of its lattice constant. For the photonic crystal within the first band gap, negative effective
permittivity or negative effective permeability has been found. Utilizing the Finite-difference time-domain method, a flat
slab imaging for TE waves in the near field has been demonstrated for the photonic crystal with effective negative
permittivity which is similar to silver superlens for TM waves. Based on these results, we can conclude that photonic
crystals in a certain frequency region can indeed mimic not only double-negative but also single-negative metamaterials.
Two kinds of novel spatial filters constructed by metamaterials and their possible applications in high-power laser
systems have been investigated. The first one can be constructed by forming a compensating bilayer of indefinite
metamaterials. It is shown that the cutoff wave vector of the low-pass spatial filter can be adjusted desirably. The second
kind of low-pass spatial filter is based on the controllable dispersion characteristics of photonic crystals. With proper
design, the higher spatial frequency components, which are incident to the filter with angles exceed a critical value, are
reflected totally because no Bloch waves of the photonic crystals can be excited. However, the lower spatial frequency
components are coupled to the self-collimating modes and permeate with high transmission. The applications of the two
novel kinds of metamaterials-based low-pass spatial filter in high-power lasers are discussed.
Metamaterials (MMs) are artificial structures, which can be engineered to satisfy the prescribed requirements. The most
important difference between an ordinary medium and a MM is that the former has a constant permeability, while the latter
has a dispersive and controllable permeability. MMs can extend the electromagnetic properties of conventional materials,
and the study of the nonlinear propagation of ultrashort pulses in MMs could lead to completely new electronic and optical
devices. In this paper, the research advances on the propagation of electromagnetic pulses in MMs with third-order nonlinear
response are briefly described. Special effort is focused on the typical nonlinear optical phenomena such as modulation
instability, bright and dark solitons.