Journal of Optoelectronical Nanostructures
Volume:1 Issue: 1, Spring 2016

Data transmission in optical systems and increased transmission distance capacity benefit by using optical amplification wavelength division multiplexing (WDM) technology. The combination of four waves (FWM) is a non-linear effect in the wavelength division multiplex (WDM), when more than two wavelengths of light in a fiber launch will occur. FWM amount depends on the channel, the channel spacing and dispersion fiber, but is independent of the bit rate. A simple equation for the spectral line width is shown. Dispersion causes distortion of the transmitted signals and needs to be compensated to achieve a long-haul system. The four-wave mixing effect have been studied as one of the factors influencing by using OPTISYSTEM Software. In this paper, a new approach for suppressing the four-wave mixing (FWM) crosstalk by using the pairing combinations of differently linear-polarized optical signals is investigated. The simulation is conducted using an eight-channel system. The proposed technique is to suppress the FWM interaction using different input powers. It has been evaluated for single-mode fiber (SMF). FWM can be strongly reduced, when the polarization technique is conducted for SMF. We also compare our new method with a conventional method to demonstrate the effect of FWM as well. The comparison was conducted at an input power range of 2 dBm. Decreasing the input power can decrease the FWM effects. In the absence of the polarization technique the FWM power was –64 dBm at an input power of 2 dBm. The FWM power decreased to less than -82 dBm at a 2 dBm input power. The system performance greatly has been improved.

The main problemswith the use of fossil fuels is the restrictions on their access and the detrimental consequences of their use which causes a threat to human health and quality of life. Consequently, the use of other energy sources has become necessary. Renewable Energy as a permanent and clean energy source is an answer to this problem. One such energy source includes photovoltaic solar energy that is widely available as a reliable energy source. Research and Development of Photovoltaic Energy in general, will reduce costs and improve efficiency in both areas. CIGS solar cells have higher efficiency in comparison with other cells. Ion implantation and doping technique offers the unique structure of a solar cells. This paper will examine the performance of solar cells with Cu In1-x Gax Se2 structure. This willbe performed by Silvaco software. Effect of doping phosphorus (p) and Natrium (Na), as well as the value of x and thethickness of the various layers of the solar cell, on the efficiency of the cell, have been studied.

In this paper the effects of transmittance, dispersion angle and diffusion length on the quantum efficiency of solar cells (QESC) have been simulated and investigated. Optical path technic is used for simulation. The results show that base thickness, diffusion length, dispersion angle, number of optical confinement path and transmission angles have an extremely effects on the QESC. Simulation results show that for optical paths with and QE can be achieved to 72% which is approximately 12% more than. The simulation results with grating in SC and reflecting about 100% at the end of the device show that QE increase to ٪47 with which is more than the results of device without grating. So the results show that the QESC increase with increasing the dispersion angle and diffusion length in the grating device.

In the present paper, resonant frequencies and modes of a three-atom photonic molecule and a photonic crystal placed within a cavity are numerically calculated. First, governing formulation in transverse electric field mode (TE) is obtained using Maxwell equations. Then, an algorithm based on a finite difference scheme and matrix algebra is presented. The algorithm is then implemented in a computer code developed by the authors. In the first run, resonant modes and frequencies of a linear three-atom molecule in the cavity are calculated. Calculations show that by increasing molecule length,the frequencies first come closer to each other but further increase reverses the process.Such a behavior is related to external cavity walls. In the case of photonic crystal in cavity, calculations show that the field distributions in the ground and first excited states are similar to the case where the cavity is homogeneously filled. On the other hand, calculations show that increasing the optical constant of the crystal decreases the frequencies. Such phenomenon is justified by the fact that light speed is slow in medium of high optical constants.

In this paper, scattering of a plane and monochromatic electromagnetic wave from a nano-wire is simulated using surface integral equations. First, integral equationsgoverning unknown fields on the surface is obtained based on Stratton-Cho surface integral equations. Then, the interaction of the wave with a non-plasmonic as well as a palsmonic nano-wire is considered. It is shown that in scattering of the wave from the non-plasmonic nano-wire the simple phenomena of refraction and transmission occur. On the other hand, the interaction of TM polarized light with plasmonic nano-wire excites surface plasmon waves. Simulations show that no surface plasmon is excited in interaction of TE polarized light with plasmonioc nano-wire. It is observed that, while increasing the frequency of incident light, the regime of scattering goes from electrostatic limit to simple geometric limit through diffraction region. In continuation, charge distribution induced by surface plasmon is simulated for different times. The simulation shows that a wave-like surface charge is excited and propagates on the surface.There is a very weak charge distribution within the nano-wire indicating that no light penetrates the wire.

In this paper, a photonic crystal waveguide with point defects and lattice constant perturbations of %, -5% are being investigated. Firstly waveguide structures with constant and specific parameters are being studied and photonic band gap diagrams for TE/TM modes are depicted; then pulse propagation in the frequencies available in the band gap are shown. After that, effects of parameters like refractive indicesand radius of the rods on the band gap diagram of TE/TMmodes are evaluated. It has beenshown that, by increasing the refractive indices and radius of the rods, band gap diagrams would be shifted to lower frequency amounts.

Optical separate spatial dark and bright soliton pairs in steady-state case in one dimension, for a series circuit consisting of two-photon photorefractive (PR) crystal are investigated. Each crystal can be supported the spatial soliton, and at least one must be photovoltaic. The two solitons are known collectively as separate spatial soliton pairs with dark–dark, bright–dark and bright–bright. Results show that when an optical wave has a spatial extent much less than the width of the crystal, only the dark soliton can effect on the other soliton by light-induced current, while the bright soliton doesnt have such an effect. In fact when a crystal supports a bright soliton, the light-induced current is so small that the crystal cannot act as a current source, whereas when a crystal supports a dark soliton, the light-induced current is strong enough to affect the other soliton in the other crystal. Numerical results confirm that the two solitary states remain invariant under propagation. We also show that these solitons are stable under a small perturbation.