Frequency Stop Band in an Air-Voided ZnO Photonic Crystal: A Dispersion Diagram Based Design

Abstract

Electromagnetic excitation, inside small volumes, results in perturbations which play an important role in the validation of theoretical formulations. Efforts to catch a glimpse of the action inside of the small space, can aid better thin film designs. In the non-linear anisotropic regime the results of such interactions provide important insights into the bulk level behavior of matter. Using this approach, a zinc oxide (ZnO) based photonic crystal is designed with spherical air voids. A Gaussian continuous wave excitation of the refractive index contrast (ZnO=1.9 and Air =1) photon waveguide generated thus, is characterized for the redistribution of electromagnetic field. When, centered at a specific wavelength (1.9 µm), the graph of the frequencies that can exist inside the crystal, is plotted against the limited k-space vector. The dispersion diagram that emerges shows a band of frequency states that cannot exist inside such a design. Physically this constitutes a k-space which is devoid of any detectable disturbances. Crystallographically, the reduced Brilluoin zone can be used to make a thin layer of ZnO that can act as a frequency stop layer, in a real multilayered photoelectric device.