Enhanced slow light propagation is predicted in a coupled resonator optical waveguide structure possessing highly dispersive elements using the finite-difference time-domain method. The group velocity is shown to be below 0.01co.
We present a review of recent studies into the tunability of 2D PC slab waveguides designs. The properties of dynamic, static and hybrid superlattice photonic crystals are reviewed and the mechanism of tunability and its impact on tuning the refractive and dispersion and propagation properties are presented.
A tunable two-dimensional photonic crystal (2D-PC) design is proposed in which the background medium is composed of an electro-optic material such as lead lanthanum zirconate titanate. The lattice structure is based upon the 2D triangular lattice of holes in a dielectric background; however, holes of two different radii are used and arranged in such a way to create a superlattice structure. The optical properties of this structure are modified by applying an electrical bias so that the dielectric constant is changed from 6.2 to 6.75. Numerical calculations show the band structure of the superlattice is highly modified in comparison to the triangular lattice. In particular, the first full photonic band gap decreases in width and band splitting occurs at high symmetry points of the lattice. From the analysis of the equifrequency contours resulting from the dispersion surface, the angle of refraction of an incident beam was calculated. By changing the biasing conditions on the structure, the refracted beam can be tuned >55° at an incident angle of 14°. This represents an increase of functionality over the regular triangular lattice which is tunable over 5-10° for a 1.36 change in dielectric constant.