The absorption characteristics of complex medium structures having metasurfaces comprised of columnar nanorods of gold were investigated. In this stream, a periodically arranged assembly of vertical gold nanorods of circular and elliptical cross sections, backed by chromium nanorods of the same cross-sectional size and shape, was considered to be the metasurface, and the comparative features of the absorption characteristics were emphasized. The results exhibit very high absorption corresponding to certain wavelengths in the visible span, and the absorber having elliptical gold nanorods yields a better performance than the one with circular nanorods in terms of the magnitude/smoothness of the absorption peaks.
Metamaterials have been of great interest owing to multifarious technological applications. Among various applications of scientific need, the perfect absorber kind of property of metamaterials remains prudent. Within the context, this investigation describes the filtering/absorber applications of metasurfaces comprised of columnar nanorods of gold having circular and elliptical cross-sections. The spectral features of such absorbers are investigated in terms of absorptivity in the visible to infrared (IR) regimes. The results indicate of almost perfect absorption corresponding to certain wavelengths in the IR span. Also, multiple absorption peaks would determine the filtering characteristics of the structures under consideration. It has been found that the absorber having circular nanorods exhibits better performance than the one with elliptical nanorods in terms of the magnitude/smoothness of absorption peaks in the entire electromagnetic spectral region of interest; the case of elliptical nanorods makes the absorption spectra to yield too much of flickers in the IR range of wavelength.
The paper reports investigation of a rather new type of optical fiber composed of three layers with the outermost region being radially anisotropic liquid crystal material, and the inner two regions as linear, homogeneous, and isotropic dielectrics. As such, the anisotropy remains in the outermost section of fiber. The core–clad interface of the inner dielectric regions is assumed to be loaded with conducting tape helix structure. It has been found that the width of the tape as well as the helix pitch angle are the effective parameters to govern the dispersion characteristics. Taking into account the zero-order guided modes, the effects on confinements due to the amalgamation of birefringence (optical property of liquid crystal) and tape helix pitch (geometrical/structural property of perfect conductor) are reported. The obtained results are compared with the case of a conducting sheath helix loaded liquid crystal fiber structure, and it has been found that the conducting tape helix loadings would be more useful than the sheath helix loaded fibers.
This communication describes a rather new type of optical fiber composed of three layers with the outermost region
being radially anisotropic liquid crystal, and the inner dielectric core-clad interface is loaded with conducting tape helix
structure. Similarly to the fibers embedded with conducting sheath helix, the introduction of tape helix too would throw
the impact of altering the dispersion features of the guide. However, the situation becomes more complex in the sense
that, apart from the helix pitch angle (as generally considered in the case of sheath), the width of tape helix structure
becomes the additional factor to affect the dispersion characteristics. We consider the core and the inner clad sections as
made of linear, homogeneous and isotropic dielectrics, and the anisotropy remains in the outermost section due to the
presence of nematic radially anisotropic liquid crystal material. Taking into account the zero-order guided modes in the
fiber structure, effects on confinements due to the amalgamation of birefringence (optical property of liquid crystal) and
tape helix pitch (geometrical/structural property of prefect conductor) are reported. Results reveal that such liquid crystal
fibers with conducting tape helix loadings would be more useful than the sheath helix loaded fibers.
Wave propagation in optical mediums greatly depends on the materials of which the guides are composed. Among the other forms of optical mediums, liquid crystals are both inhomogeneous and optically anisotropic in nature, and exhibit strong electro-optic behavior, which allows alternation in their optical properties under the influence of external electrical fields. These features make optical fibers containing liquid crystals greatly useful for fabricating many optical devices for practical applications. As such, the analytical investigation of wave propagation through liquid crystal optical fibers, particularly a three-layer fiber with radially anisotropic liquid crystal material in the outermost clad section, remains interesting. The power confinement in the liquid crystal section of such fibers can be enhanced for these to be efficiently used in optical coupling and/or sensing applications. Furthermore, a control over the dispersion characteristics, and, hence, the confinement of power, in such fibers may be imposed by making the guide even more complex in the form of introducing a conducting sheath helix structure at the core-inner clad interface.