Symmetrical analysis of the defect level splitting in two-dimensional photonic crystals

In this paper doubly degenerate defect states in the band gap of the two-dimensional photonic crystal are studied. These states can be split by a convenient distortion of the lattice. Through analogy with the Jahn–Teller effect in solids, we present a group theoretical analysis of the lifting of the degeneracy of doubly degenerate states in a square lattice by different vibronic modes. The effect is supported by the supercell plane-wave model and by the finite difference time domain technique. We suggest ways for using the effect in photonic switching devices and waveguides. Photonic crystals are of importance for numerous applications involving light modulation [1]. One such useful system based on photonic crystals is the high-Q photonic band gap (PBG) resonant cavity that can be realized by introducing a point defect into an otherwise regular photonic lattice which induces the existence of exponentially decaying states that appear within the stop band. Interest in the construction of active tunable elements has led to the idea of introducin