PT-Symmetry is one of the interesting topics in quantum mechanics and optics. One of the demonstration of PT-Symmetric effects in optics is appeared in the nonlinear directional coupler (NLDC). In the paper we numerically investigate the stability of temporal bright solitons propagate in a PT-Symmetric NLDC by considering gain in bar and loss in cross. By using the analytical solutions of perturbed eigenfunctions and corresponding eigenvalues the stability of temporal bright solitons is studied numerically. Three perturbed eigenfunctions corresponding to the two eigenvalues are examined for stability. The results show that the two degenerate eigenfunctions are unstable while other one is stable which have important result that the eigenfunctions are equilibrium function but not stable for all cases. Stability is tested by using energy of perturbed soliton that propagate thought the length of NLDC. In addition, the behavior of solitons under instable perturbation in a PT-Symmetric NLDC can be used to design integrated optics at Nano scales, for ultrafast all optical communication systems and logic gates. Manuscript profile

Thin films of tin sulfide/cadmium sulfide (SnS/CdS) were prepared by
thermal evaporation method at room temperature on a glass substrate and then annealed
at different temperature with the aim of optimizing the optical properties of the material
for use in photovoltaic solar cell devices. The effect of annealing on optical properties
of SnS/CdS film was studied in the temperature range of 100 to 400 °C with steps of
100 °C. The films were characterized by optical absorption spectra. The optical
constants such as band gap, refractive index (n) and extinction coefficient (k) were
calculated on different annealing temperature and in the wavelength range of 250 nm to
750 nm. Analysis of the optical absorption coefficient demonstrated the presence of
direct optical transition and the corresponding band gap values showed enhancement as
deposition annealing temperature increased. The energy band gap in the range 2.20 eV –
3.18 eV has been obtained for a film as-deposited which increases clearly with
increasing annealing temperature. The refractive index and extinction coefficient both
decrease notably with increasing annealing temperature. Manuscript profile

In this paper we numerically investigate the effect of relative phase on the
stability of temporal bright solitons in a Nano PT- Symmetric nonlinear directional
coupler (NLDC) by considering gain in bar and loss in cross. We also study the effect of
relative phase on the output perturbed bright solitons energies, in the range of   0 to
 180 . By using perturbation theory three eigenfunctions and corresponding
eigenvalues were derived analytically. These eigenvalues behave like equilibrium points
and are not stable in all cases. Stability of these perturbed solitons under the effect of
relative phase are examined and show that temporal bright solitons are almost unstable in
the range of   0 to  90 , but they keep their solitary shapes in the range of   90
to  180 . In addition the evolution of normalized energies in these ranges are
investigated.
Output pulse energy at bar and cross strongly depend on the relative phase. This effect
in a PT-Symmetric NLDC can be used for designing all-optical ultrafast self-switches
and logic gates and Nano structures. Manuscript profile

Cobalt (Co) doped Zinc Oxide (ZnO) thin films, containing different amount
of Cobalt nanoparticles as the Co doping source, deposited by the sol–gel spin coating
method onto glass via annealing temperature at 400˚C, have been investigated by optical
characterization method. The effect of Co incorporation on the surface morphology was
clearly observed from scanning electron microscopy (SEM) images. Optical
conductivity and optical constants such as absorption coefficient, reflectivity, extinction
coefficient, and refractive index as a function of photon energy were calculated, and it
was found that the doping with Co led to decrease absorption coefficient, extinction
coefficient, refractive index and bandgap energy, while the optical conductivity
increased at higher photon energies. The optical band gap depends on the Co doping
level and on the particle size and crystallinity of the films and is in the range of 3.05–
3.17 eV. The optical band gap widening is proportional to the one-third power of the
carrier concentration. Manuscript profile