Enlargement of nontransmission frequency range in photonic crystals by using multiple heterostructures

We show theoretically that the nontransmission frequency range of photonic crystals can be substantially enlarged as desired by using multiple heterostructures. This photonic multiple heterostructure consists of different photonic crystals. The constituent photonic crystals are chosen such that the nontransmission frequency ranges of the adjacent constituents are arranged in a way similar to the type-II lineup of the band-gaps in semiconductor heterostructures. Examples in the two-dimensional systems are demonstrated theoretically by using transfer matrix methods.