Numerical study of The Remittances of Axially Excited Chiral Sculptured Zirconia Thin Films

The transmission and reflection spectra from a right-handed chiral sculptured zirconia thin film are calculated using the coupled wave theory and the Bruggeman homogenization formalism in conjunction with the experimental data for the relative dielectric constant of zirconia thin film. The dielectric dispersion function effect on these spectra appeared in wavelengths shorter than the Bragg wavelength. In wavelengths larger than the Bragg wavelength, the dispersion of the dielectric function can be ignored. The results achieved in this work are consistent with the experimental data (Wu et al. (2000)). A shift towards shorter wavelengths is observed for the Bragg peak with increasing the void fraction, which is in agreement with the theoretical work of Lakhtakia (2000). Sorge et al. (2006) also found this effect in their experimental results on TiO2 chiral thin films, while they also found that unlike our results the intensity of the reflectance of the Bragg peak decreases with increasing the void fraction. This difference between our theoretical work and Sorge et al. (2006) experimental work can be related to the structural difference between idealized theoretical model for chiral films and that obtained in experimental work. In the latter, as Sorge et al. (2006) have pointed out the experimental films exhibit a large amount of scattering due to the highly complex and non-ideal structure that the individual chiral elements exhibit.Comment: 19 pages, 7 figure

Interaction of plasmon-exciton in a columnar dielectric thin film with a structural defect excitonic thin film

In this research, the coupling of surface plasmon-polariton and surface exciton-polariton in a multilayer structure of metallic medium and columnar dielectric thin film with excitonic spacer in Kretschmann configuration theoretically is investigated; using transfer matrix method. The effect of structural parameters such as the length of columns of columnar thin film and the rise angle of them, the refractive index of prism, the void fractions of columnar thin film and the thickness of excitonic medium on coupling are studied. The results showed that the coupling becomes strength by decreasing the length of columns of dialectic medium and refractive index of prism. Also, by reducing the volume fraction of air in columnar thin film, the coupling becomes stronger as the thickness of the excitonic medium increases and the ultra- strong coupling was obtained at fv=0.2. The energy spectrum of plexciton branches in terms of detuning frequency indicates the anti-crossover behavior of plexciton modes, which includes the coupling strength of the modes from the medium to ultra-strong region