Modifications in the band structure of a 2-dimensional Kerr-nonlinear photonic crystals

Modifications in the band structure of a 2-dimensional photonic crystal composed of a square array of circular air holes drilled in a Kerr-type nonlinear dielectric material are investigated. Special attention is paid on the position and width of the overlap region of TE and TM band gaps. Angular frequencies of the modes in the whole band structure are found to redshift (blueshift) for a positive (negative) Kerr susceptibility. Although the observed shift in the midgap frequencies of the band gaps increases for higher angular frequencies, the lower edges of TE and TM band gaps appear to be more sensitive to nonlinearity than the upper edges. Broadening (contraction) of the band gaps is related to the relative shift of the band edges. Parameters for polarizing-device applications are discussed on the basis of band structure engineering.