Light diffraction from a bilayer lattice of microspheres enhanced by specular resonance

Dominance of the specular resonance from constituent bispheres in the scattering from a cluster of several microspheres was evidenced on the basis of rigorous calculations and experiments. It was found that the experimentally observed efficient diffraction from a bilayer lattice containing a larger number of microspheres similarly originates from specular resonance in unit bispheres. Observed diffraction behavior was accurately reproduced by use of a diffraction theory of a 2D lattice, in which the scattering property of a single bisphere was incorporated as a structure factor.