Dielectric photonic crystal as left-handed medium and metal infiltrated opal as a system of connected resonators.

摘要

Materials with simultaneously negative epsilon and mu in some frequency range are known as left-handed materials (LHMs). They are extensively studied because they provide a negative refraction at the interface with a regular materials (RM) and can be used for creation of a flat lens, known as the Veselago lens (VL). These lenses may create an image of a three-dimensional (3D) object and also they may have "superlensing" properties, which means that their image may be sharper than the wavelength of the light used for this imaging.; Two-dimensional (2D) dielectric photonic crystals (PC's) have been extensively studied numerically to show that for propagating modes in the frequency range where the group velocity is negative and isotropic. These crystals are LHMs. Numerical study of the transmission and refraction of a plane wave reveals negative refraction and gives the negative macroscopic epsilon and mu for the propagating modes. The superlensing properties come from amplification of evanescent waves (EWs). Such amplification has been recently found theoretically for the hypothetical LHM (HLHM). It has been shown that the PC's behaving like a LHM for propagating modes does not provide universal amplification of evanescent waves. However, the amplification may (or may not) appear due to some reasons other than negative mu and epsilon. For example, the amplification might be due to surface waves that are not related to the dielectric properties of the PC. Such an amplification may provide an improvement of the image in the near-field region, but it does not affect the image near the far-field focal point of the Veselago lens. Simulation results of the intensity distribution near the far-field focal point of Veselago lens are in very good agreement with the analytical results obtained by two different methods.; The construction of the multifocal Veselago lens predicted earlier is proposed on the basis of a uniaxial photonic crystal consisting of cylindrical air holes in silicon that make a triangular lattice in a plane perpendicular to the axis of the crystal. The period of the crystal should be 0.44mum to work at the wavelength 1.5mum. The lens does not provide superlensing but the half-width of the image is 0.5lambda. The lens is shown to have wave guiding properties depending on the substrate material. (Abstract shortened by UMI.)