External tunability of optical filter in symmetric one-dimensional photonic crystals containing ferroelectric and ITO material defect

This study theoretically investigates the properties of the defect mode with external controllability in a symmetric 1D defective photonic crystal (1DDPC) composed of a ferroelectric layer and two pairs of thin Indium-tin oxide (ITO) as defect layers. The tunability of defect mode was investigated, as a function of the electric field alongside the incident angle. The results reveal that the defect mode wavelength can be tuned by variations of the electric field and the incident angle as well Because of the polarization-dependent optical properties of ferroelectric layer, the shift trend in the defect mode is shown to also rely on the polarization. The proposed structure can be good candidate in designing an externally tunable optical filter with potential applications in electro-optical devices.