Arafa H. Aly

The properties of cutoff frequency in two-dimensional superconductor photonic crystals

In this paper, by means of frequency-dependent plane wave expansion method we investigate the properties of photonic band structures in two-dimensional superconductor photonic crystals. Effects of cut-off frequency are investigated by various parameters such as filling factor, the lattice constant alteration, threshold frequency of the superconductor, and shape of the rods as well. We show that the cut-off frequency can be efficiently tuned by the operating temperature. Moreover, it can be tailored by changing the dielectric constant of the background and the threshold frequency of the superconductor material.

Cutoff frequency in metamaterials photonic crystals within Terahertz frequencies

By employing the characteristics matrix method, we have investigated the transmission properties of one-dimensional dielectric–semiconductor metamaterial photonic crystals (PC) at Terahertz (THz) range theoretically. The numerical results show the appearance of cutoff frequency within THz range. Furthermore, the thicknesses of the constituents materials and the filling factor have a significant effect on the cutoff frequency. The proposed structure may be useful in many applications, particularly in THz frequency regions.

STUDY OF PHYSICAL PARAMETERS ON THE PROPERTIES OF PHONONIC BAND GAPS

In this work, we have introduced a comprehensive study concerning with the effects of some physical parameters on the dispersive properties of 1D phononic crystal (PnC). We have treated the propagation of elastic (in-plane) waves incident normally on 1D PnC. Based on the transfer matrix method, the reflection coefficients are calculated and plotted for the plane waves. We have studied many physical parameters effects on the properties of PnCs such as type of surrounding material, type of composites materials, temperature and propagation of waves in defect structures. Also the phenomenon of local resonance was discussed in this survey. These results can be useful in many applications such as sound suppressions and temperature sensor materials.

Ionizing particle detection based on phononic crystals

Most conventional radiation detectors are based on electronic or photon collections. In this work, we introduce a new and novel type of ionizing particle detector based on phonon collection. Helium ion radiation treats tumors with better precision. There are nine known isotopes of helium, but only helium-3 and helium-4 are stable. Helium-4 is formed in fusion reactor technology and in enormous quantities during Big Bang nucleo-synthesis. In this study, we introduce a technique for helium-4 ion detection (sensing) based on the innovative properties of the new composite materials known as phononic crystals (PnCs). PnCs can provide an easy and cheap technique for ion detection compared with conventional methods. PnC structures commonly consist of a periodic array of two or more materials with different elastic properties. The two materials are polymethyl-methacrylate and polyethylene polymers. The calculations showed that the energies lost to target phonons are maximized at 1u2009keV helium-4 ion energy. There i...

Low band gap frequencies and multiplexing properties in 1D and 2D mass spring structures

This study reports on the propagation of elastic waves in 1D and 2D mass spring structures. An analytical and computation model is presented for the 1D and 2D mass spring systems with different examples. An enhancement in the band gap values was obtained by modeling the structures to obtain low frequency band gaps at small dimensions. Additionally, the evolution of the band gap as a function of mass value is discussed. Special attention is devoted to the local resonance property in frequency ranges within the gaps in the band structure for the corresponding infinite periodic lattice in the 1D and 2D mass spring system. A linear defect formed of a row of specific masses produces an elastic waveguide that transmits at the narrow pass band frequency. The frequency of the waveguides can be selected by adjusting the mass and stiffness coefficients of the materials constituting the waveguide. Moreover, we pay more attention to analyze the wave multiplexer and DE-multiplexer in the 2D mass spring system. We show that two of these tunable waveguides with alternating materials can be employed to filter and separate specific frequencies from a broad band input signal. The presented simulation data is validated through comparison with the published research, and can be extended in the development of resonators and MEMS verification.

Propagation of acoustic waves in 2D periodic and quasiperiodic phononic crystals

In this study, we have investigated theoretically the propagation of longitudinal sonic waves in 2D periodic and aperiodic (quasiperiodic) phononic crystals. Fibonacci sequence has been used to generate the aperiodic structure. The effect of transformation from 2D periodic to aperiodic structure has been elucidated by calculating the transmission coefficient. The consequences of inserting a circular solid cylinder inside a host water matrix have been repeated at the same calculating conditions. Changing filling fraction has been used to tune the stop band width.

Tunable properties of one-dimensional photonic crystals that incorporate a defect layer of a magnetized plasma

In this paper, we theoretically investigate the transmittance characteristics of one-dimensional defective photonic crystal in microwave radiations based on the fundamentals of the characteristic matrix method. Here, the defect layer is magnetized plasma. The numerical results show the appearance of defect peaks inside the Photonic Band Gap. The external magnetic field has a significant effect on the permittivity of the defect layer. Therefore, the position and intensity of the defect peak are strongly affected by the external magnetic field. Moreover, we have investigated the different parameters on the defect peaks as the plasma density, the thickness of the plasma layer and the angle of incidence. Wherefore, the proposed structure could be the cornerstone for many applications in microwave regions such as narrowband filters.

STUDY OF THE ANOMALY PHENOMENA FOR THE HYBRID SUPERCONDUCTOR-SEMICONDUCTOR JUNCTIONS

The conductance anomaly behavior for superconductor-semiconductor-superconductor junctions is investigated. We propose a potential profile at the interface which depends on the intrinsic parameters of the junctions, e.g. carrier concentration. The tunneling probability is derived by the WKB method and the corresponding conductance is expressed in terms of the tunneling probability through Landauer–Buttiker formula. The results show a zero-bias anomaly (ZBA) for the dependence of conductance on bias voltage. Also, the oscillatory behavior of the conductance with the magnetic field, due to the chaotic behavior of the junction.

ELECTROMAGNETIC WAVE PROPAGATION CHARACTERISTICS IN A ONE-DIMENSIONAL METALLIC PHOTONIC CRYSTAL

We theoretically studied electromagnetic wave propagation in a one-dimensional metal/dielectric photonic crystal (1D MDPC) consisting of alternating metallic and dielectric materials by using the transfer matrix method. We performed numerical analyses to investigate the propagation characteristics of a 1D MDPC. We discuss the details of the calculated results in terms of the electron density, the thickness of the metallic layer, different kinds of metals, and the plasma frequency.

Optical properties of one-dimensional defective photonic crystal containing nanocomposite material

We have obtained the optical properties of one-dimensional defective photonic crystals containing nanocomposite materials of Ag as a defect layer in UV region; the permittivity of nanocomposite materials depends on plasmon frequency of metal nanoparticles. Our analysis is based on the fundamentals of the transfer matrix method. We have investigated the effect of many parameters such as metal thickness, volume fraction, and defected dielectric materials on the intensity of a defect layer.