M. Karaaslan

New-Generation Chiral Metamaterials Based on Rectangular Split Ring Resonators With Small and Constant Chirality Over a Certain Frequency Band

Chiral metamaterials (MTMs), a new class of MTMs, provide a simpler solution for obtaining negative refraction and dynamic electromagnetic response. Many research groups have been studying chiral MTMs asking for strong chiral behaviors such as optical activity and circular dichroism. These studies have generally focused on the properties of a large chirality and circular dichroism. However, small and constant chirality over a certain frequency band have not been queried so far in the literature. In fact, this area is mostly ignored by the researchers. This study numerically and experimentally focuses on small and constant chirality with a new-generation planar chiral MTM based on rectangular split ring resonators (SRRs), in details by using two different geometries. We have successfully obtained small chirality values by using the proposed designs, which can be easily integrated into many interesting applications such as transmission and antireflection filters or polarization control devices.

Electromagnetic absorbance properties of a textile material coated using filtered arc-physical vapor deposition method

We explore the structure of a textile absorber in terms of its electromagnetic and absorption properties in the microwave region. Its absorption characteristics are similar to those reported for various metamaterial-based absorbers, exhibiting absorption as high as 98% at resonance. In addition, the angular behavior of the absorption properties of the sample reveal incident angle independency, which is the other added value of the study. Also, the suggested textile absorber has a simple configuration, which introduces flexibility to adjust its material properties and easily tune its structure to suit other frequencies. The proposed textile absorber and its variations have myriad potential applications in radar technology, long distance radio telecommunication, and so on. Although in its current state the proposed structure provides almost perfect absorption covering a wide range of microwave C-Band, the developing technology will soon allow manufacturing textiles that can manipulate lights, leading to the design of invisibility cloak and other science fiction devices besides finding important application areas in medical science.

Photonic band gap engineering in two-dimensional photonic crystals and iso-frequency contours

We have theoretically investigated photonic band structures of two-dimensional (2D) photonic crystals (PCs) in air background. The lattices consist of the rotated and modified square dielectric rods. The influence of opto-geometric parameters of designed unit-cell structures are analyzed in terms of opening frequency gaps and appearing tilted band graphs by applying plane wave expansion method. Optimum structures with large photonic band gaps are notified. In order to get “gap maps”, the gaps as a function of the size and the rotation angle of the square rods are calculated. So, the band gaps of transverse magnetic and transverse electric polarization modes indicate symmetry in point of the rotation angle and these band gaps overlap. Thus, the smallest width of the narrow air veins is founded as 0.06a. The results show almost 40 nm complete width of the air veins for mid-gap wavelength λ = 1.55 μm. This result shows the fabrication capability of these optimized PC structures.

Implementation of a perfect metamaterial absorber into multi-functional sensor applications

Perfect metamaterial absorber (MA)-based sensor applications are presented and investigated in the microwave frequency range. It is also experimentally analyzed and tested to verify the behavior of the MA. Suggested perfect MA-based sensor has a simple configuration which introduces flexibility to sense the dielectric properties of a material and the pressure of the medium. The investigated applications include pressure and density sensing. Besides, numerical simulations verify that the suggested sensor achieves good sensing capabilities for both applications. The proposed perfect MA-based sensor variations enable many potential applications in medical or food technologies.

New generation chiral metamaterials based on omega resonators with small and smooth chirality over a certain frequency band

In this paper, we have designed, simulated and analyzed a new generation chiral metamaterials (MTMs) with two geometries. There are various types of chiral MTM structures in the literature and almost all of them are indented to be designed for high level of chirality. In fact, small chirality and its application areas were mostly ignored by researchers. In this sense, our study is one of the pioneer works for this type of research. Each structure based on omega resonators (ORs) with small chirality value is investigated both numerically and experimentally. The results are in very good agreement which will lead us to conclude that our structures can be easily used as devices for controlling polarization, EM wave transmission filtering, antireflection and so on for a wide range of the EM spectrum.

Polarization angle independent metamaterial absorber based on circle-shaped resonators with interference theory

We theoretically and numerically designed a perfect metamaterial absorber at microwave frequencies. The proposed design has a very simple geometry, wide band properties and provides perfect absorption for all polarization angles which is one of the most desired properties for an absorber structure to be used in the applications where the source polarization is unknown. In order to explain the absorption mechanism both numerical and theoretical analyses are carried out. Designed structure offers a perfect absorption at around 9.8 GHz. The resonance frequency does not change depending on the source wave polarization. In addition, it can be easily reconfigured for THz and infrared regimes for different applications such as sensors, defense systems and stealth technologies.

New generation planar chiral metamaterials with small and constant chirality over a certain frequency band

Chiral metamaterial (MTM) researchers generally concentrate and aim to obtain large chirality with optical activity in certain frequencies. However, new generation planar chiral MTM which have small and constant/flat chirality over a certain frequency band have not queried by this time in literature. In fact, this area is mostly ignored by researchers. This study, first one according to best of our knowledge in the literature, is investigating the small and constant/fixed chirality and focuses on the new generation planar chiral MTM based on circular split ring resonators (SRRs), in details. It can be seen from the results that the proposed model can provide small and constant/flat chirality over a certain frequency band and thus it can be used to design myriad novel devices such as polarization rotators, and electromagnetic transmission and antireflection filters for several frequency regions.

Meanderline Based Microwave Polarization Rotator and Antireflector

We showed analytically that a chiral slab can exhibit both optical activity and antireflection. Oblique incident waves depending on permittivity, chirality and thickness of bulk chiral material are investigated. The analytical calculations are numerically achieved by meander line metamaterial.