Transmittance spectrum in a regular one-dimensional photonic crystal and with the insertion of a YBa2Cu3O7-x defective layer

We theoretically calculate the transmittance spectrum of TE polarization in a one-dimensional photonic crystal that is embedded in air, composed alternating layers of the YBa2Cu3O7-x superconductor and the BaTiO3 dielectric, using the transfer matrix method. In the first part of this study, we found the transmittance spectrum of the regular structure (without defects). We observe that new photonic band gaps (PBGs) can be observed with a continuous increase in width by increasing the thickness of the superconductor layer and by maintaining the temperature and the thickness of the dielectric in case of normal incidence. By increasing the temperature while maintaining the layer thickness fixed, the dielectric constant of the superconductor can be increased, resulting in a small shift of the transmittance spectrum at long wavelengths. In addition, the PBG widths are observed to be sensitive to an increase in the angle of light incidence. In the second part of this study, the translational symmetry of the crystal is broken by inserting a YBa2Cu3O7-x defective layer. Further, we demonstrate the existence of a defective mode in the visible range within the PBG. By increasing the thickness of the defective layer, this defective mode can be observed at long wavelengths. Additionally, the defect mode can be tuned by increasing the temperature and by maintaining a constant crystal thickness. We can also observe a shift to short wavelengths of the defect mode while increasing the angle of incidence.