الفهرس 
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Abstract
Now, plasmonics play an essential role in many optical systems due to their unique properties and ability to direct light below the diffraction limit. Moreover, the integration of optical systems and electronic systems can be achieved using these plasmonic nanostructures. Since the advent of those devices, an accurate numerical model is urgently needed to model these plasmonic structures. The metamaterial based photovoltaic absorber as a plasmonic device is subject to extensive research work all over the world. Metamaterials open new opportunities for optical absorbers by engineering the values of the electromagnetic permittivity ɛ_rand the magnetic permeability µ_r of the material to show unique electromagnetic properties not found in natural materials such as negative refractive index, invisible occlusion, and near-zero electrical permittivity. Meta-based absorbers can also be manufactured within a specific range of wavelengths or over multiple bands. However, broadband metamaterial absorbers are challenged by the narrow bandwidth of surface plasmon polariton and polariton magnetic resonance. In this thesis, a metamaterial-based heat absorber device is designed, studied and analyzed as an example of plasmonic photovoltaic devices. Accordingly, a new wavelength-selective absorber based on 2D gratings has been proposed and analyzed. The proposed structure consists of magnesium fluoride MgF_2 on top of a molybdenum (Mo) metallic layer. In addition, a two-dimensional rhombus of Mo is placed on top of the (〖MgF〗_2) layer. The optical properties of the proposed absorber are calculated using the time-domain finite difference method, using the Lumerical software based on the time-domain finite difference method. In this regard, the effect of different parts of the design was studied to improve the absorption capacity over a wide range of wavelengths. In addition, a model based on the inductance and capacitor (LC) model is studied and proposed to explain the improvement in the ability to absorb in the proposed design. In addition, the effect of light incident with an angle of inclination from θ = 0 to 60˚ has been studied for both the transverse magnetic (TM) and transverse electric (TE) waves. High absorption is achieved over a wide range of wavelengths from 300 to 4000 nm with a high efficiency of photon-to-heat conversion up to 81.71% at a temperature of 1000 K. This thesis is organized as follows: Chapter 1 It starts with a general brief introduction on the importance of optical plasmonic devices and their various applications, including thermal photovoltaic absorption devices, and then presents the objectives and content of the thesis. Chapter 2 reviews the basic idea and the importance of plasmonics and the photovoltaic system and its working principle, structure, features and components. It also shows an explanation of each component and its function, with an explanation of each component and its function. Chapter 3 reviews the different mathematical numerical methods and then presents in detail the finite differences time domain method that is used in modeling the proposed design. Chapter 4 presents the design and analysis of an absorbing device based on metamaterials over a wide range of wavelengths. Finally, Chapter 5 presents a summary of the thesis, main conclusion and some future suggestions for this work.