Tuning the band structures and electromagnetic density of modes in fused Silica slab by acoustic waves

Abstract

The band structures and electromagnetic density of modes in fused Silica slab perturbed by acoustic waves have been modelled and studied. The strain caused by the acoustic wave modulates the refractive index of the fused Silica slab. This leads to the periodic variation of refractive index in the slab along propagation direction similar to one dimensional photonic crystal. The band structures, spectral transmittance and electromagnetic density of modes in induced one dimensional photonic crystal have been calculated using transfer matrix method and Wigner time phase approach. A wide photonic band gaps with enhanced magnitude of density of modes at the edges are observed for the photonic crystal induced by longitudinal acoustic wave. It is found that the photonic band gaps are shifted to higher frequencies with the increase in angle of incidence for both polarized electromagnetic waves. The photonic bandgap and density of mode are tuned by varying the acoustic frequencies. Also, the increase in acoustic amplitude leads to enhanced density of modes at the edges of photonic band gaps.