Dispersion engineering in regular and graded photonic crystals to promote anomalous refraction effects are studied by the authors of this book, from the basic concepts to experimental demonstration via nanofabrication considerations. Self-collimation, ultra- and negative refraction, second harmonic generation, mirage and invisibility effects, which lead to an unprecedented control of light propagation at the (sub-) wavelength scale for the field of integrated nanophotonics, are detailed and commented upon.
In Chapter 1, the fundamental concepts for the exploitation of light propagation in photonic crystals are reviewed, based on the exploitation of band structures and equi-frequency surfaces. Special attention is devoted to hole and pillar dielectric lattice nanofabrication techniques, aiming to operate for wavelengths at the micron scale. Chapter 2 studies various flat lens configurations, based on regular or graded photonic crystals, both theoretically and experimentally in the field of linear optics, with special attention being paid to resolution limits. In the third and final chapter, generalizations of graded photonic crystals with an index gradient in one or two dimensions of space are investigated in order to demonstrate mirage effects or wavelength demultiplexing at very short scales. Furthermore, the mixing of hole and pillar lattices using the transformation optics tools opens the way for two-dimensional cloaking devices. Here, theoretical concepts are supported by an experimental demonstration of controlled light propagation at the wavelength scale.