Dielectric and Semiconducting Photonic Crystals: Optical Response, Absorption Mechanisms and Device Relevance

Abstract

Dielectric and semiconducting photonic crystals (PCs) constitute an important class of periodic optical media where the refractive index contrast and periodicity enable strong control over electromagnetic-wave propagation. In such structures, macroscopic optical properties can be effectively described using phenomenological parameters such as refractive index, dielectric permittivity, susceptibility and conductivity, particularly because the optical wavelength is typically much larger than the interatomic spacing. The optical response of dielectric/semiconductor multilayers is primarily governed by light–matter interaction through electronic polarization and absorption due to band-to-band transitions. While dielectrics generally exhibit dominant absorption in the ultraviolet region owing to large band gaps, semiconductors show significant absorption in the visible and near-infrared regime due to comparatively smaller band gaps. By applying Maxwell’s equations and boundary conditions at interfaces, key spectra such as transmittance, reflectance and absorption can be modeled, allowing systematic tuning of photonic band gaps and pass bands. These properties make dielectric–semiconductor PCs suitable for designing frequency-selective filters, reflectors and integrated photonic components, where controlled propagation and attenuation are essential for optical and optoelectronic applications.