ABSTRACT
The concept of photonic crystals (PhCs) was put forward in the 1970s and 1980s with the aim to enable control on light emission, propagation, and absorption by purposive structuring of materials.1 This is achieved through interference of the incident and scattered electromagnetic waves in the materials possessing periodic or quasiperiodic variation of the dielectric permittivity in one or more dimensions. The collection of photon eigenmodes in PhCs is called the photonic band gap (PBG) structure. Since scattering becomes especially efcient if the size of any obstacle approaches the wavelength, λ, the unit cell size in such architectures is inevitably in match to the wavelength, a ~ λ. Originally, PhCs were designed assuming frequency-independent permittivities of their frameworks. By now, the variability of such PhCs is practically exhausted. That is why in the race for novel functionalities one has to look into physical effects beyond the interference paradigm. The energy exchange between electromagnetic waves and electronic resonances in the PhC material can be considered as one possible option.
