Design and characteristics of two-dimensional photonic crystal with KTP defect

The plane wave expansion method is applied to simulate the band gap of a tunable twodimensional photonic crystal micro cavity based on controlling the refractive index of defect medium. KTiOPO4(KTP) crystal is introduced to the planar photonic crystal as point defect, with its refractive index controlled by alternating current according to electro-optic effect. Numerical calculations and experimental results show that, with the refractive index of KTP increasing, the normalized frequencies of defect modes shift downward. The number of band gaps of the square lattice reduces, and the band gap of the triangle lattice narrows．