Externally tunable multichannel filtering applications of organic material based 1D magnetic cold-plasma photonic crystals.

In the present research work, we employed the transfer matrix method (TMM) in addition to MATLAB software to examine the transmission properties of various organic-based one-dimensional (1D) magnetic cold-plasma photonic crystals (MCPPhCs). The proposed structures were found to be made up of periodic layers of organic materials and magnetic cold-plasma (MCP) at normal incidence. An external magnetic field (B) polarized in right-hand (RH) and left-hand (LH) configurations was applied on 1D MCPPhCs. In this study, four organic materials, namely pentane, hexane, heptane, and octane, were chosen to design four 1D photonic crystals (PCs), named as PC1 (pentane-MCP), PC2 (hexane-MCP), PC3 (heptane-MCP), and PC4 (octane-MCP). Our results indicated that the central frequency of the resonant peaks of unit transmission inside the photonic band-gap (PBG) of the respective organic PCs could be tuned towards the higher or lower frequency side by applying B polarized in RH and LH configurations, respectively. We also studied the effect of the period number N to produce closely spaced N-1 transmission channels of unit transmission inside the PBG of all four organic PCs. By increasing the period number N we could increase the number of transmission channels inside the PBG as per our desire. These multiple resonant peaks of unit transmission inside PBG could be easily modulated inside the PBG to accommodate new frequencies by applying B polarized in either RH or LH configurations, respectively. Moreover, our results showed that under the RH configuration, increasing B resulted in a shifting of the resonant peak towards the higher frequency side with a reduction in its full width half maximum (FWHM), whereas the findings were the opposite in the case of increasing B under the LH configuration. These findings may be beneficial for designing externally tuneable organic chemical sensors in the microwave frequency region.

Plastic Deformation of Single-Crystal Diamond Nanopillars.

Diamond is known to possess a range of extraordinary properties that include exceptional mechanical stability. In this work, it is demonstrated that nanoscale diamond pillars can undergo not only elastic deformation (and brittle fracture), but also a new form of plastic deformation that depends critically on the nanopillar dimensions and crystallographic orientation of the diamond. The plastic deformation can be explained by the emergence of an ordered allotrope of carbon that is termed O8-carbon. The new phase is predicted by simulations of the deformation dynamics, which show how the sp3 bonds of (001)-oriented diamond restructure into O8-carbon in localized regions of deforming diamond nanopillars. The results demonstrate unprecedented mechanical behavior of diamond, and provide important insights into deformation dynamics of nanostructured materials.

Near-infrared tunable narrow filter in a periodic multi-nanolayer doped by a superconductor photonic quantum-well.

The transfer matrix method is employed to theoretically investigate the near-infrared (NIR) narrow filter properties in a one-dimensional defective symmetric photonic crystal with a superconductor photonic quantum-well defect (PQW). The study investigates how the wavelength of the defect mode is affected by the stack number of the PQW defect structure, the thicknesses of PQW layers, the polarization, and the angle of incidence as well as the operating temperature. The results also show that the period of the PQW defect structure and the number of defect modes are independent of one another. This result differs from that of studies conducted on a common dielectric or metamaterial defect. It is noted that with an increase in the number of the defect period, the thickness of the superconductor layer, and the angle of incidence, the defect mode shows a blue-shift for both wave polarizations. On the other hand, an opposite trend is observed as the thickness of the air layer and the operating temperature increase. The results also reveal that new tunable narrow filters and optical communication devices can be achieved at NIR region in this proposed structure.

Transmittance properties in a magnetized cold plasma-superconductor periodic multilayer.

This study theoretically investigates the transmittance properties of a one-dimensional photonic crystal containing magnetized cold plasma and high-temperature superconductor materials. The cutoff frequency, as a function of the magnetic field, electron density of the plasma layer, and temperature, will be investigated. The results illustrate that the temperature, electron density, and variations of the magnetic field affect the cutoff frequency. In addition, the shift trend in the cutoff frequency proves to be dependent on the polarization due to the presence of polarization-dependent magnetized cold plasma. Moreover, in temperature-dependent transmittance, weak oscillation and intensity can be seen at higher temperatures, which is in sharp contrast to low-temperature superconductor-dielectric structures. The proposed structure could certainly provide helpful information for the design of new types of antennas, reflectors, and high-pass filters at microwave frequency.

Single-negative metamaterial periodic multilayer doped by magnetized cold plasma.

This study theoretically investigates the properties of the defect mode in a 1D defective single-negative photonic crystal containing a magnetized cold plasma defect layer. The considered photonic crystal structure is made of epsilon-negative and mu-negative metamaterials. We investigate the defect mode as a function of the thickness and the electron density of the defect layer and the magnetic field. The results show that the thickness, electron density, and variations of the magnetic field affect the frequency of the defect mode. In addition, the shift trend in the defect mode is shown to rely on the polarization due to the presence of polarization-dependent magnetized cold plasma. The results lead to some new information concerning the designing of new types of tunable narrowband filters at microwave frequency.

Analysis of defect mode in a one-dimensional symmetric double-negative photonic crystal containing magnetized cold plasma defect.

In this paper, the characteristic matrix method is employed to theoretically investigate properties of the defect mode in a 1D lossy symmetric defective photonic crystal containing two magnetized cold plasma defect layers. The considered photonic crystal is made of double-negative and double-positive materials. The defect mode, as a function of the magnetic field and the electron density, will be investigated in three different structures. The results show that the defect mode frequency can be tuned by variations of the magnetic field and the electron density as well. Due to the polarization-dependent magnetized cold plasma, the shift trend in the defect mode is shown to also rely on the polarization. The proposed structures could provide another alternative for the design of narrowband filters at microwave.