In this paper we investigate focusing properties of graded index (GRIN) photonic crystal (PC) structures which are composed of different materials with different refractive indices. GRIN PC structure is constructed from air holes in dielectric background. The holes radii are varied in the normal direction to the propagation in such a way that a parabolic effective refractive index is produced. The focusing characteristic is studied relative to the refractive index variation of background material. While increasing refractive index of background material of the GRIN PC structure, the effective refractive index of the structure increases. With increasing effective refractive index, the focusing capability of the GRIN PC structure increase and outgoing wave at focal point will be more concentrated. The result shows that the designed GRIN PC structure work very well as a focusing lens. The finite-difference time-domain (FDTD) method was employed to compute field propagation through GRIN PC structure. Also, plane wave expansion (PWE) method has been carried out to extract the dispersion properties Manuscript profile

In this study, Sendust (Fe85Si9.6Al5.4) nanostructure alloy was prepared by
mechanical alloying and was characterized by X-ray diffraction. In addition, the alloy’s
morphology and its distribution particle size were investigated by scanning electron
microscopy method. The alloyed powders were insulated with 4wt% of three different
insulating materials including polyvinyl alcohol, epoxy resin, and sodium silicate. Then,
0.5 wt% zinc stearate was added as a lubricant and the composites were formed at a
pressure of 1600 MPa in a torodial die. These cores were annealed in Ar atmosphere at
350 to 450 ºC for 1 h. Some of the magnetic parameters of the as-milled and annealed
samples were measured and compared with each other in the frequency range of 4 to
1000 kHz. The results showed that polyvinyl alcohol is not a suitable insulating agent
for insulating this alloy. In addition, the real part of the initial magnetic permeability of
the magnetic powder core insulated by sodium silicate in comparison with that insulated
by epoxy resin is a bit smaller, but more reduction of the imaginary part of former
results in an increase the Q-factor throughout measuring frequency range. The results
show that annealing is more effective on improvement of the measured magnetic
properties of the samples insulated with sodium silicate than that insulated with epoxy
resin. Manuscript profile

Using the transfer matrix method, the effect of temperature on the
transmission spectra of thermal tunable nano metallic photonic crystal filter has been
investigated. Three different materials H (high refractive index material), L (low
refractive index material) and M as a metallic layer, have been used to make this
structure. M layer is considered to be Silver. The complex refractive index of Silver is a
function of temperature and wavelength simultaneously so, the structure is tunable with
temperature and incident angle. It is found that the transmission peaks shift by changing
temperature and incident angle. At a given incident angle, they move toward higher
wavelengths by increasing the temperature. The temperature dependence of
transmission peaks is linear. At a constant temperature, they move toward the shorter
wavelengths by increasing the incident angle. Also by increasing the temperature, due to
dissipation Manuscript profile

We studied magnetophotonic crystals (MPCs) with introduced magnetic
defect layer sandwiched between magnetic and dielectric Bragg mirrors. These
magnetophotonic crystals have excellent capabilities to enhance reflection and Kerr
rotation simultaneously. By adjusting spatial configuration such as repetition numbers
of Bragg mirrors and thickness of magnetic defect layer, we achieved the Kerr rotation
angles more than 75˚ and reflection very close to 1. We briefly described the
formulation of finite element method (FEM) and transfer matrix method (TMM). The
electric field distribution and magnitude of it along the MPCs are simulated using FEM.
Using the TMM, we calculated the MO responses of MPCs. With light localization
inside the magnetic defect layer and multiple reflections in it, the magneto-optical (MO)
responses of these MPCs were significantly increased. The studied structures in this
research have high MO responses that make it suitable for designing MO elements in
highly sensitive devices and optical telecommunication tools. 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