The refraction properties of photonic crystal lattices offers methods to control the beam
steering of light through use of non-linear dispersion contours. In this paper new photonic crystal
structures, such as the square and triangular superlattices, that provide novel refractive properties
are analyzed. The property difference between rows in these structures is the hole radius Δr. The
difference in hole sizes leads to observation of the superlattice effect, that is, a change in the
refractive index Δn between opposite rows of holes. The index difference becomes a function of the
size of the smaller r2 hole area or volume due to the addition of the higher index background
material compared to the larger r1 holes. The difference in hole radii Δr = r1 - r2 is referred to as the
static superlattice strength and is designated by the ratio of r2/r1. The superlattice strength increases
as the ratio of r2/r1 decreases.
The hole size modulation creates modified dispersion contours that can be used to fabricate
advanced beam steering devices through the introduction of electro-optical materials and a
controlled bias. A discussion of these superlattice structures and their optical properties will be
covered, followed by both static and dynamic tunable device constructions utilizing these designs.
Also, static tuning of the devices through the use of atomic layer deposition, as well as active tuning
methods utilizing liquid crystal (LC) infiltration, sealed LC cells, and the addition of electro-optic
material will be discussed.