Transmittance spectra of (YBa₂Cu₃O_7-x/BaTiO₃) 1D photonic crystals: the role of GaAs and Al_xGa_(1-x)As semiconductors in the visible range

We present the transmittance spectra of one-dimensional photonic crystals embedded on two sides with air. The unit cell is composed of a YBa2Cu3O7-x superconductor as material A and a BaTiO3 dielectric as material B. The transmittance of the formed structure (AB)(N) was studied using the transfer matrix method for different parameters such as layer widths (dA and dB), the angle of incidence, and temperature. Wavelength shifts delimiting the photonic bandgaps (PBGs) are discussed in detail. We found that these wavelengths shifted toward longer values (i.e., a redshift) as the size of the layers increased and the temperature increased. However, increasing the incidence angle shifts the wavelengths to shorter values (i.e., a blueshift). In the second part of this work, we discuss the impact of inserting semiconductor layers (GaAs or AlxGa(1-x)As) with different bandgaps and varying the hydrostatic pressure, temperature, and aluminum concentration. We demonstrate that these semiconductors can also shift the PBGs and modify their widths; these findings constitute important results with implications for the design and realization of photonic filters.