Photonic and electromagnetic crystals offer unprecedented control of photons and have emerged as an important new class of optical materials. Continued developments in the analysis and calculation of photonic crystals, as well as rapid advances in nano-fabrication techniques, have enabled us to design and prototype ever more intricate and functional photonic crystal structures and devices. Novel photonic nanostructure devices such as ultrasmall channel add/drop filtering devices, new type of lasers and photonic fibers are developing rapidly. Construction of fully three dimensional photonic crystals continues to be an important aim for the development of photonic chips.

Over the past several years, even more exciting opportunities have arisen from the study of periodic structures. Metamaterials have offered a wealth of new phenomena, including negative refractive index, superlensing and cloaking. Slowing or even stopping light inside of photonic crystals is also being investigated.

Materials for fabricating photonic crystals are also expanding into all classes: organic, metallic, ceramic, magnetic, and dielectric. Combination of desirable properties and phenomena, such as nonlinearity and luminescence, from a wide variety of materials promises to bring about new and exciting applications. In PECS-VII, we hope to review the significant advances in the field and discuss future directions of photonic crystal research.