Researchers at CSIC and IFIMAC have recently reported and analyzed, in Small, Fano-like resonances in vacancy doped photonic crystals. The results show that the Fano’s parameter experiences a sign change signaling the transition from a perfect crystal exhibiting a reflectance Bragg peak, through a state where background scattering is maximum and Bragg reflectance reaches a minimum to a point where the system reenters a low scattering state recovering ordinary Bragg diffraction. This behavior is explained by considering the field enhancement at the defects and the correlation between scatterers and vacancies in terms of the emerging covariance between the optical paths and the polarizabilities. [Full article]
