Optical properties and photonic modes in patterned semiconductor systems

The optical response of a photonic crystal slab, where a dielectric grating is the elementary building block, is computed in the semiclassical framework, and compared with the dispersion curves of the bulk. The formalism adopted for the calculation employs the eigenmodes of a single layer as basis set for electromagnetic field expansion; it allows us to compute photonic crystal slab optical response as well as dispersion curves. Recently, the method was generalized to take into account spatial dispersion effects close to an exciton resonance of the system, and it was possible also to study the transition from dissipative to dispersive regime for a system under Bragg condition. The role of bulk and surface waves in the system is discussed as a function of the layer number N in the range N = 1 ÷ ?. The “mirror effect”, observed in rectangular self-sustained gratings, due to the interplay among traveling, evanescent and guided waves, is recovered. This effect can be preserved also in the semi-infinite photonic crystal for selected values of the physical parameters. The role of light polarization in 1D and 2D systems is briefly discussed.