Photonic band gaps in anisotropic photonic crystals

Photonic band gaps can be improved in photonic crystals fabricated from ani sotropic materials. In three-dimensional photonic crystals, the anisotropy can open partial band gaps in simple lattices such as face-centered-cubic, body-centered-cubic, and simple-cubic lattices of dielectric spheres in air , where no absolute band gap exists. Yet, this anisotropy will reduce origi nally existing band gap. Such an anisotropy can substantially improve the a bsolute band gap in two-dimensional photonic crystals due to the quasi-inde pendent adjustment of the refractive indices for the E- and H-polarization modes in anisotropic materials. (C) 2000 Elsevier Science B.V. All rights r eserved.