Optimization of the temperature dependence of a defect mode in a binary defective photonic crystal

One-dimensional defective binary photonic crystal is considered with the structure (AB)(N) D(AB)(N), where A (TiO2) and B (SiO2) are the layers constituting the photonic crystal and D is the defect layer. The temperature dependence of the defect mode is investigated by considering both thermo-optic and thermal expansion effects. As the refractive indices and thicknesses of the photonic crystal layers are varied by temperature, the properties of the photonic crystal, such as bandgap and defect mode, are modified. Thus, we propose a tunable transmission filter operating in the visible region of the spectrum. It is found that the transmittance peak shift of the defect mode can be enhanced with the increase of both thermo-optic and the thermal expansion coefficients of the defect mode. As an example, we consider a photonic crystal with the structure (TiO2-SiO2)(6)/SiOC/(TiO2-SiO2)(6) and a transmittance peak shift of the defect mode of 1.51 nm is obtained for a temperature increase of 100 degrees C.