  We apply Bloch analysis to the study of finite periodic cascading of
microring resonators. Diagonalization of the standard transfer matrix approach
not only allows to find an exact analytic expression for transmission and
reflection, but also to derive a closed form solution for the field in every
point of the structure. To give more physical insight we analyze the main
features of the transmission resonances in a finite chain and we give some
hints for their experimental verification
