Solution box: SOLBOX-07

Photonic crystals are well-known electronic devices that enable modification, transformation, and selection of light or, more generally, electromagnetic waves [1]. Even though they have a long history of more than 100 years, these structures are becoming increasingly popular, thanks to the rapid developments in nanotechnology and material science, enabling the design and fabrication of very small details [2]. As in all areas of electromagnetics, numerical simulations of photonic crystals are important, since they can provide the analysis and investigation of these structures before their fabrication [3–12]. Three-dimensional simulations, where the photonic crystals are modeled as finite, aperiodic, and possibly inhomogeneous structures, are especially essential to understanding the electromagnetic responses of various designs [8, 11].