Muharrem Karaaslan

Polarization Angle Independent Perfect Metamaterial Absorbers for Solar Cell Applications in the Microwave, Infrared, and Visible Regime

We design, characterize, and analyze a new kind of metamaterial (MTM) absorber (MA) in difierent frequency regions for the solar cell applications. This MTM based structure is particularly presented in a range of the solar spectrum in order to utilize the solar energy efiectively. The proposed MTM based solar cell provides perfect absorption for both infrared and visible frequency ranges and can be used for the realization of more e-cient new solar cells. The structure is also tested in terms of the polarization angle independency. The suggested MA has a simple conflguration which introduces ∞exibility to adjust its MTM properties to be used in solar cells and can easily be re-scaled for other frequency ranges. Our experimental results in microwave frequencies conflrm the perfect absorption for the resonance frequency and agree with the simulation results. This means that the developed MA for solar cells will ofier perfect absorption in infrared and even in visible frequencies.

DESIGN OF POLARIZATION AND INCIDENT ANGLE INSENSITIVE DUAL-BAND METAMATERIAL ABSORBER BASED ON ISOTROPIC RESONATORS

Polarization and incident angle independent metamaterial-based absorber (MA) which acts as a strong dual-band resonator is designed and constructed. Besides, a method to design single/dual- band MA is presented in detail. The proposed model is based on isotropic ring resonator with gaps and octa-star strip (OSS) which allows maximization in the absorption because of the characteristic features of the structure. Re∞ection and absorption responses are obtained both numerically and experimentally and compared to each other. Two maxima in the absorption are experimentally obtained around 90% at 4:42GHz for the flrst band and 99:7% at 5:62GHz for the second band which are in good agreement with the numerical simulations (95:6% and 99:9%, respectively). The numerical studies verify that the dual-band MA can provide perfect absorption at wide angles of incidence for both transverse electric (TE) and transverse magnetic (TM) waves. The proposed model can easily be used in many potential application areas such as security systems, sensors, medical imaging technology.

Dual-Band Polarization Independent Metamaterial Absorber Based on Omega Resoanator and Octa-Star Strip Configuration

Dual-band metamaterial absorber (MA) with polarization independency based on omega (›) resonator with gap and octa- star strip (OSS) conflguration is presented both numerically and experimentally. The suggested MA has a simple conflguration which introduces ∞exibility to adjust its metamaterial (MTM) properties and easily re-scale the structure for other frequencies. In addition, the dual- band character of the absorber provides additional degree of freedom to control the absorption band(s). Two maxima in the absorption are experimentally obtained around 99% at 4:0GHz for the flrst band and 79% at 5:6GHz for the second band which are in good agreement with the numerical simulations (99% and 84%, respectively). Besides, numerical simulations validate that the MA could achieve very high absorption at wide angles of incidence for both transverse electric (TE) and transverse magnetic (TM) waves. The proposed MA and its variations enable myriad potential applications in medical technologies, sensors, modulators, wireless communication, and so on.

Asymmetric Transmission of Linearly Polarized Waves and Dynamically Wave Rotation Using Chiral Metamaterial

The asymmetric transmission of the linearly polarized waves at normal incidence through the lossy anisotropic chiral structure is demonstrated. The proposed chiral metamaterial structure is composed of bi-layered discontinuous cross-wire-strips, and it is utilized in order to realize polarization rotation. Firstly, the theoretical relations between the incident polarization and the polarization rotation are derived using transmission matrices. Secondly, a strong and dynamically asymmetric transmission of linearly polarized electromagnetic wave through the chiral metamaterial has been demonstrated for microwave region, both by simulation and experimentally. The experiment results are in good agreement with the simulation ones. It can be seen from the results that the proposed chiral metamaterial structure can be used to design novel polarization control devices for several frequency regions.

TRANSMISSION TUNNELING THROUGH THE MULTILAYER DOUBLE-NEGATIVE AND DOUBLE-POSITIVE SLABS

Transmission tunneling properties and frequency response of multilayer structure are theoretically presented by using transfer matrix method. The structure is composed of double-negative and double-positive slabs which is sandwiched between two semi-inflnite free space regions. Double-negative layers are realized by using Lorenz and Drude medium parameters. The transmission characteristics of the proposed multilayer structure based on the constitutive parameters, dispersion, and loss are analyzed in detail. Finally, the computations of the transmittance for multilayer structure are presented in numerical results. It can be seen from the numerical results that the multilayer structure can be used to design e-cient fllters and sensors for several frequency regions.

Chiral Metamaterial Based Multifunctional Sensor Applications

In this work, sensor abilities of a chiral metamaterial based on split ring resonators with double splits (SRDS) are demonstrated both theoretically and experimentally in X band range. This study is based on transmission measurements and simulations monitoring the resonance frequency changes with respect to the thickness of the sensing layer and permittivity values. Experimental and simulated results show that the resonance frequency of the chiral metamaterial based SRDS sensor is linearly related to the permittivity and the thickness of the sensor layer which creates a suitable approach for sensing environment and organic parameters. When the sensor layer filled with the related material, changes in the tissue temperature, sand humidity and calcium chloride density lead to resonance frequency changes. The physical mechanisms are explained by using both equivalent circuit model and the fundamental sensitivity theorem of chiral sensors. This is the first study investigating a sensing mechanism based on the chiral metamaterials in X band range.

Polarization‐insensitive FSS‐based perfect metamaterial absorbers for GHz and THz frequencies

New perfect frequency selective surface (FSS) metamaterial absorbers (MAs) based on resonator with dielectric configuration are numerically presented and investigated for both microwave and terahertz frequency ranges. Also, to verify the behaviors of the FSS MAs, one of the MAs is experimentally analyzed and tested in the microwave frequency range. Suggested FSS MAs have simple configuration which introduces flexibility to adjust their FSS metamaterial properties and to rescale the structure easily for any desired frequency range. There is no study which simultaneously includes microwave and terahertz absorbers in a single design in the literature. Besides, numerical simulations verify that the FSS MAs could achieve very high absorption levels at wide angles of incidence for both transverse electric and transverse magnetic waves. The proposed FSS MAs and their variations enable many potential application areas in radar systems, communication, stealth technologies, and so on.

Design of Polarization- and Incident Angle-Independent Perfect Metamaterial Absorber with Interference Theory

A perfect metamaterial absorber is realized and its properties are theoretically, numerically and experimentally investigated at microwave frequencies. In addition, polarization and incident angle independencies are also tested for the structure. Theoretical, numerical and experimental results show that the proposed model has many advantages compared to those in the literature, such as perfect absorption, polarization and incident angle independencies, very simple design, and operation over a sufficiently wide band. A simple configuration is chosen for the proposed model so that it can be easily tuned for other frequency regimes to realize new absorbers for applications such as sensors and stealth technology.

Polarization and angle independent perfect metamaterial absorber based on discontinuous cross-wire-strips

This study presents design, fabrication, and measurement of a metamaterial absorber (MA) based on discontinuous cross-wire-strip (CWS) resonators. This suggested that MA has a simple geometry configuration and introduces perfect absorption approximately 99.79% at 3.42 GHz for simulation and 99.72% at 3.44 GHz for experiment. In addition, the designed model can be used to realize the broadband absorber for desired frequency ranges. Besides, numerical simulations validate that the MA could achieve very high absorptions at wide angles of incidence for both transverse electric and transverse magnetic waves. The experimental results are in good agreement with the numerical simulations. Moreover, this study presents a numerical analysis in order to explain physical interpretation of MA mechanisms in detail. The proposed model and its variations enable myriad potential applications such as stealth and radar technologies.

Design and analysis of perfect metamaterial absorber in GHz and THz frequencies

The new perfect metamaterial absorber (MA) based on square resonator with gap configuration is numerically (for GHz and THz frequency regime) and experimentally (for GHz frequency regime) presented and investigated. The proposed MA has a simple configuration which introduces flexibility to adjust its metamaterial properties and easily rescale the structure for other frequency regimes. In addition, polarization and incident angle independencies of the proposed model are analyzed for the THz frequency regime. The suggested structure could achieve very high absorption at wide angles of polarization and incident angles for both transverse electric and transverse magnetic waves. At resonance frequencies, absorption results are realized around 99.99% at 5.48 GHz and 99.92% at 0.865 THz for their respective frequency regimes. Besides numerical results in GHz and THz frequencies, experimental results are also obtained for GHz frequency regime. The proposed MA and its variations enable myriad potential applications in areas such as defense systems, communication, stealth technologies, and so on.