We studied the electronic structure as well as the dielectric, optical, and phonon properties of PbTiO3 / CaTiO3 / SrTiO3 ferroelectric superlattices, based on the density functional theory, using the Perdew–Becke–Johnson-generalized gradient approximation exchange-correlation functional. According to the results, the superlattice under investigation possessed a semiconducting phase with an indirect band gap of 1.84 eV. The results obtained for the partial density of states were indicative of a strong hybridization between the Ti-3d and O-2p states, which affected the amplitude of the Coulomb interaction and ferroelectric property. Regarding the optical properties, we calculated and analyzed the dielectric function and, accordingly, the refractive index, reflectivity, absorption coefficient, energy loss function, and optical conductivity. Thermal vibrations of the lattice were calculated along the high-symmetry path of the first Brillouin zone. Phonon dispersion data revealed stability at point Γ, while ferroelectric and dielectric responses of superlattice could be in unstable modes at other points of the Brillouin zone. Our results comprehensively present the electronic structure, dielectric function, plasmonic features, and dynamical stability based on phonon calculations, which are all essential for novel functional device applications.
We have designed some holographic gold gratings in 700-1100nm wavelength range for stretching and compressing
pulse in CPA technology. These gratings optimized by Gsolver software based on rigorous coupled-wave analysis
(RCWA) for TM polarized light in the 1st order (littrow mount) and have super Gaussian profiles. We also shown
dependency of diffraction efficiency (DE) to depth and duty cycle of super Gaussian gold gratings in 1064nm.
A few holographic silver gratings with maximum diffraction efficiency in the 700-1100nm wavelength range were designed. They can be attractive for stretching and compressing pulse in CPA (chirped pulse amplification) technique. KPP1206 photoresist was used to model the final pattern on photoresist thin film. This paper was devoted to consider super Gaussian gratings. Therefore, approximately identical exposure energy density intervals were used for optimizing grating profile. Accordingly, the Genetic Algorithm (GA) was employed by Grating Solver software to optimize groove spacing, groove depth and groove shape of the grating for TM polarized light in the 1st order (littrow mount).Also, Dependency of diffraction efficiency (DE) to depth and duty cycle of super Gaussian silver gratings in 1064nm was shown.
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