Defect modes of a two-dimensional photonic crystal in the presence of acoustic wave

Defect modes of a photonic crystal modulated by propagating acoustic wave are investigated using supercell plane-wave expansion method. It is show that as a result of dielectric permittivity modulation resonant frequencies of defect modes change harmonically in time with the same frequency as the acoustic wave. Modulation level is larger for low-frequency acoustic wave and decrease with increasing frequency of sound due to spatial averaging of dielectric permittivity changes in defect region.