Designing photonic structures of nanosphere arrays on reflectors for total absorption

By means of full electrodynamic simulations, we investigate structures that can totally absorb light minimizing all reflections. Such efficient absorbers of visible and infrared light are useful in photovoltaic and sensor applications. Our study provides a simple and transparent analysis of the optical properties of structures comprising a resonant cavity and a reflector, which are the basic ingredients of a resonant absorber, based on general principles of scattering theory. We concentrate on periodic arrays of metallic or dielectric spherical particles in front of metallic or dielectric mirrors and show that tuning the material absorption could turn resonances in the structures into total absorption bands. Perfect absorption is predicted in metallic sphere arrays but also for Si spheres on a metallic substrate, moreover, by replacing the substrate below the Si spheres with a lossless dielectric Bragg mirror an all-dielectric-perfect-absorber is designed. (C) 2013 AIP Publishing LLC.