Disorder-induced Fano resonance in 1D photonic crystals

We present a general picture of optical properties of 1D disordered photonic structures. Calculations of optical spectra were performed with use of transfer matrix technique. It was found that the Fano resonance between disorder-induced Fabry-Perot continuum and narrow Bragg bands is one of the most fundamental features of optical spectra. We also consider a novel class of optical materials - structures composed of periodical arrangement of ordered components and components with fluctuating dielectric constant, i.e. “disordered” components. For disordered components, the average dielectric constant is equal to that of ordered components, i.e. dielectric contrast on average vanishes. We show that such materials possess photonic band structure which can be considered as an inverted of that found in photonic crystals, i.e. instead of Bragg stop bands we observe Bragg pass bands. A detailed study shows that the main mechanism behind these extraordinary optical properties is the localization of light.