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

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

Recently soliton propagation in few-mode fiber has been
studied. In this paper, we used commercially few-mode
fiber for investigating the soliton propagation. Three
modes exist in this fiber, by considering polarization, we
have six propagation modes. Initially, we calculate the
propagation mode, effective cross-section, and dispersion
for each mode then soliton propagation in fiber modes with
respect to phase are simulated. The nonlinear effect causes
XPM which affects propagation modes to each other. By
various values of phase, the first maximum energy transfer
between modes is calculated. We find minimum
normalized length 0.66 which equal to a length of 23.3
meters of silica fiber for energy exchange. The energy
exchange can be used as a basis for all-optical switching.
Interestingly, these effects cause energy transfer between
different modes and strongly depend on the phase
difference. So, the results of this simulation can be used to
design all-optical self-switches and all optical logic gates. Manuscript profile

We study the supercontinuum generation in a nonlinear
silica single layer plasmonic waveguide. A major part of
spectral broadening is related to soliton dynamics when an
ultra-short pulse is launched in waveguide with anomalous
GVD. Production of supercontinuum with 10th, 15th and
30th, orders bright solitons by considering all the nonlinear
effects and dispersions i.e., inter-pulse Raman scattering,
self-steepening, self-phase modulation, cross phase
modulation, which indicates the existence of a
supercontinuum propagation about 20 times broadening
than initial width of input spectrum.
Also, we consider the absorption effect of plasmonic
waveguide by calculating propagation length from
propagation constant. The propagation length of plasmonic
is compared with the waveguide length and nonlinear
length. At wavelength 1.22μm, the propagation length is
obtained in the order of waveguide length which means one
can consider the effect of absorption cannot alter the
results. The nonlinear plasmonic waveguides are suitable
for integrated photonics because of subwavelength
confinement of plasmonic waveguides. Manuscript profile