In this study, we simulated and analyzed a plasmonic waveguide modulator based on a single layer of graphene. It includes a graphene sheet, which sandwiches between two layers of silicon dioxide. Then, some gates are arranged on either side of the waveguide on a periodic structure. When an electric field is applied perpendicular to the waveguide plate, the Fermi level of graphene under the gates changes. Detailed analysis is performed by the method of lines based on Maxwell's equations along the propagation direction of the waveguide. Computation of the multi-gate device starts by examining the effect of the Fermi level. The transmission coefficient of the magnetic-field norms of the modulator is calculated by varying the parameters, such as Fermi level, length, gates number, and distance between the gates to achieve optimized design of the modulator device with very small dimensions. The results show that at higher Fermi levels, where the imaginary part of the effective index of the waveguide is close to zero, the reflection is dominant and absorption is low. Therefore, the modulator length becomes so long that it is more than one hundred nanometers. At lower Fermi levels, where the amount of the imaginary part of the effective index is significant, the absorption is dominant. At this range, a one-gate device is sufficient for modulation. Consequently, the designed minimum device length becomes equal to six nanometers for the ten-micrometer wavelength. Furthermore, the design is carried out in other wavelengths.

The interface of photovoltaic (PV) systems to the grid requires an efficient control strategy to operate, control, and improve power quality. The output voltage of the solar array, which may be accompanied by significant voltage variations, must be controlled and converted to a higher voltage for grid connection applications of photovoltaic system by a DC‐DC converter that commands more attention. Recently, due to the increasing use of renewable sources, multilayer structure with different structures and designs to provide power and stability has been researched because the output voltage of solar arrays is usually low, so it is increasing to DC‐to‐DC converters, needed with optimal interest and efficiency. In this paper, a method to improve the performance of DC–DC converter used in PV system by using a combined design of forward and fly‐back is presented. Due to the fact that isolated converters, flyback, and forward converters have a simple structure and are easy to control, but this converter is affected by high stress voltage. Therefore, this converter cannot be used for high power applications. To solve this problem, it has been improved in the proposed converter with the overlay and triple induction technique, which is a very good improvement on the voltage gain parameters in the short duty cycle. The voltage drop across the semiconductor switch is reduced. The investigations performed that the proposed DC/DC converter in Simulink MATLAB has been simulated. The results show that the suggested converter has an ideal efficiency of roughly 82.86% and provided higher voltage gain, decreased voltage stress, and reduced voltage jumps caused by disconnection.

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