Photonic crystals (PhC) are periodic arrangements of optical materials (usually dielectrics) with a high refractive index contrast. the periodicity and the index contrast give a PhC unusual properties, such as high dispersion or a photonic band gap (PBG).
The PICAZZO library contains a number of different classs to help you design photonic crystal components. The generic layout classes allow you to define your own map of the unit cells in a rectangular or triangular photonic crystal lattice, enabling you to define any arbitrary layout in a periodic lattice.
Common components, such as W1 waveguides (trangular lattices with one row of holes missing) are predefined.
Hetero-crystals allow you to build a photonic crystal waveguide with sections of different lattice constant. This can be used to make wavelength-selective mirrors or cavitites with an extremely high quality factor.