Effect of external perturbations on phonon-polariton modes and photonic band gap in piezoelectric crystal

- The dielectric constant is determined by incorporating the temperature dependence of the acoustic and optical parameters.
- The behavior of polariton dispersion as a function of superlattice period and temperature in a novel PSL is analyzed.
- The PBG of PC consisting of novel PSL as one of the layer is investigated theoretically.
- It is concluded that the ωTO is shifted towards the lower frequency region when the temperature increases.
- The novelty of this research, the PBG occurs both in THz and GHz regions.

The behavior of polariton dispersion as a function of superlattice period and temperature in a novel piezoelectric superlattice (PSL) by using Lithium Niobate is analyzed theoretically. By implementing the temperature coefficients of each acoustic and optical parameters, the dielectric permittivity is determined. The modes are shifted and the polaritonic gap decreases with temperature. The transmission properties of a one-dimensional novel photonic crystal having novel piezoelectric superlattice as one of the layers and air as another layer have been investigated by means of transfer matrix method. The photonic band gaps can be tuned by altering the thicknesses of the layers, incidence angle, the number of periods and temperature. When the thickness of the PSL layer changes from μm to mm, the photonic band gap is found to be shifted from THz to GHz region. The evolution of these results provides a guideline for designing optoacoustic devices, filters, and sensors.