This paper demonstrates the design of an Arrayed Waveguide Gratings (AWG) based Optical switch. In the design both physical and network layer analysis is performed. The physical layer power and noise analysis is done to obtain Bit Error Rate (BER). This has been found that at the higher bit rates, BER is not affected with number of buffer modules. Network layer analysis is done to obtain performance in terms of packet loss rate and average delay. Analysis presented in the paper clearly reveals that there is a minimum amount of power required, which is necessary for the satisfactory performance of switch both at physical and network layer.

VLSI technology is currently dealing with a serious challenge, as the exponential growth of density in VLSI and CMOS chips has reached its limit. Power dissipation in VLSI chip refers to heat generation, which is a real barrier against traditional CMOS technology. Irreversible logic leads to problems such as energy dissipation, heat generation, information loss and slow computations. We need a new technology for solving these problems. Using reversible logic can help solve this problem. In next generation of Optical computers, electrical circuits and wires will be replaced by several Optical fibers and these systems will be more efficient because they will be cheaper, lighter, and more compact without interference. Based on Optical computations, several Optical switches have been proposed for future applications. One of these switches is the Mach-Zehnder switch. Its behavior and the reversible circuits, which can be made with this switch is studied in this article. Finally, we introduce and design three new all-Optical reversible gates named NFT, SRK and MPG, which are effective in designing all-Optical reversible logical circuits such as flip-flops and other all-Optical reversible sequential circuits. We also simulate one all-Optical reversible circuits implemented with Mach-Zehnder switch and provide simulation challenges and solutions to overcome these challenges.

A physical model is develpoed for operation of a functional quantum well optoelectronic integrated device (QW-OEID). Based on the model, static and dynamic characteristics of the device is analyzed numerically considering the effects of parameters such as internal Optical feedback and lateral diffusion of carriers for both amplification and switching modes of operations.

This paper studies the uncertain nonlinear dynamics of a MEMS Optical switch addressing electrical, mechanical and Optical subsystems. Recently, MEMS Optical switch has had significant merits in reliability, control voltage requirements and power consumption. However, an inherent weakness in designing control for such systems is unavailability of switch position information at all times due to the saturated output characteristics, which is aggravated by considering disturbances. In order to circumvent this problem, two nonlinear observers based on the first order and second order sliding mode approach are designed to estimate the state variables of the device subject to external disturbances. The nonlinear observers are then utilized in the control system to maintain robust stability and tracking performances. The newly invented second order sliding mode controller can remove the chattering phenomena as the main drawback of the first order sliding mode controller. Furthermore, since second order sliding mode control is not robust against disturbances/uncertainties which vary with states, a new time-varying second order sliding mode control is proposed to enhance the robust performance of the controller without estimating any switching time. Simulation results show that the proposed observer and control have good tracking ability and robustness against disturbances.

We propose a new ring resonator side-coupled M-Z interferometer all-Optical switch through the pumped nonlinear directional coupler. By controlling pump power P to lead the coupler reflectivity r approaching to 1, the resonator finesse will be enhanced dramatically, and then the minimum switching power in silica-based practice devices can be obtained. As a sample, we use a nonlinear coupler made by two erbium-doped fibers, and launch a 514.5nm-pump light into one of the cores to make the reflective- index difference between two cores. Based on the asymmetric-coupler theory, we simulate the relationship between r and P, and show that the required pump power is only 0.8Mw for r →1.

We solve the coupled mode equations governing the chalcogenide nonlinear fiber Bragg gratings (FBGs) numerically, and obtain the bistability characteristics. The characteristics of the chalcogenide nonlinear FBGs such as: switching threshold intensity, bistability interval and on-off switching ratio are studied. The effects of FBG length and its third order nonlinear refractive index on FBG characteristics are investigated. We obtain an interesting result that independent of the third order nonlinear refractive index; there exists an optimum FBG length of about 6 mm at which the on-off switching ratio becomes maximized. It is also found that by increasing the nonlinearity, the maximum value of on-off switching ratio decreases. The results of this paper can be mainly used for designing allOptical switches and memories.

In this paper, a novel plasmonic Optical switch based on graphene is designed and simulated with better features and four channels. Each of these channels has an equal width of 20nm which constructed from graphene ribbons spaced at a distance of 30nm from each other. The operation of device is based on the modulation of graphene chemical potential in each channel by using applied voltage. This means that by application of a proper voltage the transmission of input in every channel can be controlled and hence the switching can be occurred. Performance characteristics of this Optical switch achieves a relatively high transmission with very low loss at the frequency of 30THz. Also in this structure the amount of crosstalk is remarkably low. This structure has been investigated in different chemical potentials in which one of it’ s best status occurs in chemical potential of 0. 4eV. All analyses and simulations have been performed in Lumerical and MATLAB.

Background and aim: It is possible to use light sources suxh as lasers to destruct melanosomes and treat pigmented skin lesions. One of the most commonly used laser systems is Q switched ruby laser with a wave-length of 694 nm. This study was performed to evaluate the efficacy of the Q switched ruby laser in the treatment of pigmented skin lesions including lentigines (simplex or solar) and café-au-lait macules.Materials and Methods: After physical examination for ruling out the possibility of malignancy by two dermatologists, patients were treated with Q switched ruby laser. Response to treatment was categorized in four groups of equal interval according to the 0-100% lesion lightening. Results: Ninetyy patients including 81 patients with solar lentigo and 9 cases of lentigo simplex were recruited into this study. Mean standard deviation (SD) of the number of treatment sessions for solar lentigo and lentigo simplex cases were 1.0 0.5 and 3.6 1.3, respectively. Although the mean of sessions was increased in darker skin types, there was no statistically significant difference between different skin types (p=0.335). In addition, there was no significant relation between mean treatment sessions and location of the lesions (p=0.685). Cure rate was 100% in all lentigo cases and after a mean SD of 8.7 2.3 months follow up there was no recurrence. Also, there was neither pigmentary change nor folliculitis during treatment. In 7 cases with cafe-au-Iait macules, the mean SD score of improvement was 2.4 0.8, which was achieved after 3.1 0.4 treatment sessions. In 6 cases whom were followed up for 10.2 3.1 months, despite primary disappearance, recurrence of café-au-lait macules was observed.Conclusion: It seems Q switched ruby laser is an appropriate method for treatment of lentiginous lesions in caucasians with Fitzpatrick's skin types II to IV.