arXiv subjects

Muhammad Faryad

Publications and source records attributed to Muhammad Faryad.

33 records · Page 2Linked to original sources

arXiv2019

Surface plasmon-polariton waves obliquely guided along interface containing periodicity direction of one-dimensional photonic crystal

We recently formulated the canonical boundary-value problem of propagation of surface plasmon-polariton (SPP) waves along the direction of periodicity of a one-dimensional photonic crystal. Here we present the general formulation of that canonical problem supporting the oblique propagation of SPP waves in the interface plane. The general dispersion equation has been obtained using the rigorous coupled-wave approach for the oblique propagation and numerically solved using the Muller's method. A periodicity in the wavenumbers of the SPP waves was observed. Furthermore, the regions of high losses for the SPP waves, dubbed as plasmonic bandgaps, were observed in the photonic band diagram of the SPP waves. These plasmonic bandgaps can be used to construct optical filters for the SPP waves.

physics.optics↗

arXiv2019

Electromagnetic surface waves guided by the planar interface of isotropic chiral materials

The propagation of electromagnetic surface waves guided by the planar interface of two isotropic chiral materials, namely materials $\calA$ and $\calB$, was investigated by numerically solving the associated canonical boundary-value problem. Isotropic chiral material $\calB$ was modeled as a homogenized composite material, arising from the homogenization of an isotropic chiral component material and an isotropic achiral, nonmagnetic, component material characterized by the relative permittivity $\eps_a^\calB$. Changes in the nature of the surface waves were explored as the volume fraction $f_a^\calB$ of the achiral component material varied. Surface waves are supported only for certain ranges of $f_a^\calB$; within these ranges only one surface wave, characterized by its relative wavenumber $q$, is supported at each value of $f_a^\calB$. For $\mbox{Re} \lec \eps_a^\calB \ric > 0 $, as $\left| \mbox{Im} \lec \eps_a^\calB \ric \right|$ increases surface waves are supported for larger ranges of $f_a^\calB$ and $\left| \mbox{Im} \lec q \ric \right|$ for these surface waves increases. For $\mbox{Re} \lec \eps_a^\calB \ric < 0 $, as $ \mbox{Im} \lec \eps_a^\calB \ric $ increases the ranges of $f_a^\calB$ that support surface-wave propagation are almost unchanged but $ \mbox{Im} \lec q \ric $ for these surface waves decreases. The surface waves supported when $\mbox{Re} \lec \eps_a^\calB \ric < 0 $ may be regarded as akin to surface-plasmon-polariton waves, but those supported for when $\mbox{Re} \lec \eps_a^\calB \ric > 0 $ may not.

physics.optics↗

arXiv2018

Rigorous formulation of surface plasmon-polariton-waves propagation along the direction of periodicity of one-dimensional photonic crystal

A rigorous formulation of the canonical boundary-value problem is presented to find the surface plasmon-polariton waves guided by the interface of a one-dimensional photonic crystal and metal along the direction of the periodicity. The problem is formulated using the rigorous coupled-wave approach and a dispersion equation has been obtained. The Muller's method and Newton--Raphson method were used to obtain illustrative numerical results of the dispersion equation. The solutions were found to converge as the number of Floquet harmonics increased. This formulation does not require the computation of the photonic bandgaps and directly computes the surface-wave modes. This formulation could engender new applications of plasmonics exploiting the neglected interface along the direction of periodicity of the one dimensional photonic crystals.

physics.optics↗

arXiv2017

Excitation of the Uller-Zenneck electromagnetic surface waves in the prism-coupled configuration

A configuration to excite the Uller-Zenneck surface electromagnetic waves at the planar interfaces of homogeneous and isotropic dielectric materials is proposed and theoretically analyzed. The Uller-Zenneck waves are surface waves that can exist at the planar interface of two dissimilar dielectric materials of which at least one is a lossy dielectric material. In this work, a slab of a lossy dielectric material was taken with lossless dielectric materials on both sides. A canonical boundary-value problem was set up and solved to find the possible Uller-Zenneck waves and waveguide modes. The Uller-Zenneck waves guided by the slab of the lossy dielectric material were found to be either symmetric or anti-symmetric that transmuted into waveguide modes when the thickness of that slab was increased. A prism-coupled configuration was then successfully devised to excite the Uller-Zenneck waves. The results showed that the Uller-Zenneck waves are excited at the same angle of incidence for any thickness of the slab of the lossy dielectric material, whereas the waveguide modes can be excited when the slab is sufficiently thick. The excitation of Uller-Zenneck waves at the planar interfaces with homogeneous and all-dielectric materials can usher new avenues for the applications for electromagnetic surface waves.

physics.optics↗

arXiv2015

Enhancement of dynamic sensitivity of multiple surface-plasmonic-polaritonic sensor using silver nanoparticles

Multiple surface plasmon-polariton (SPP) waves excited at the interface of a homogeneous isotropic metal and a chiral sculptured thin film (STF) impregnated with silver nanoparticles were theoretically assessed for the multiple-SPP-waves-based sensing of a fluid uniformly infiltrating the chiral STF. The Bruggemann homogenization formalism was used in two different modalities to determine the three principal relative permittivity scalars of the silver-nanoparticle-impregnated chiral STF infiltrated uniformly by the fluid. The dynamic sensitivity increased when silver nanoparticles were present, provided their volume fraction did not exceed about 1%.

physics.optics↗

arXiv2014

Experimental excitation of multiple surface-plasmon-polariton waves with 2D gratings

The excitation of multiple SPP waves as Floquet harmonics was demonstrated in structures fabricated as one-dimensional photonic crystals (PCs) on top of two-dimensional gold gratings. Each period of the PC comprised nine layers of silicon oxynitrides of different compositions, and each PC had either two or three periods. Absorptances for obliquely incident $p$- and $s$-polarized light were measured in the 500--1000-nm wavelength regime and the sharp bands in the absorptance spectra were compared with the solutions of the underlying canonical boundary-value problem. The excitation of multiple surface-plasmon-polariton (SPP) waves as Floquet harmonics was confirmed. The structures demonstrated broadband absorption with overall weak dependences on the incidence angle and the polarization state of the incident light, and has potential application for harvesting solar energy.

physics.optics↗

arXiv2014

Observation of the Uller-Zenneck wave

The Uller-Zenneck wave has been theoretically predicted to exist at the planar interface of two homogeneous dielectric materials of which only one must be dissipative. Experimental confirmation of this century-old prediction was obtained experimentally by exciting the Uller-Zenneck wave as a Floquet harmonic of non-zero order at the periodically corrugated interface of air and crystalline silicon in the 400-to-900-nm spectral regime. Application for intra-chip optical interconnects at ~850 nm appears promising.

physics.optics↗

arXiv2014

Grating-coupled excitation of the Uller-Zenneck surface wave in the optical regime

The excitation of the Uller-Zenneck surface wave in the optical regime was theoretically investigated for planar as well as periodically corrugated interfaces of two homogeneous, isotropic dielectric materials, with only one of the two being dissipative. A practical configuration involving the planewave illumination of a planar interface of the two partnering materials was found to be unsuitable for experimental confirmation of the existence of this surface wave. But, when the interface was periodically corrugated, the Uller-Zenneck wave was found to be excited over a wide range of the angle of incidence. Air and crystalline silicon were identified as suitable partnering materials for experiments in the visible and ultraviolet spectral regimes.

physics.optics↗

arXiv2014

Evolution of surface-plasmon-polariton and Dyakonov-Tamm waves with the ambichirality of a partnering dielectric material

The planar interface of an isotropic homogeneous metal and an ambichiral dielectric material can guide surface-plasmon-polariton waves. The planar interface of an isotropic, homogeneous dielectric material and an ambichiral dielectric material can guide Dyakonov-Tamm waves. In either instance, we found that, as the ambichiral partnering material evolves into a finely chiral material, the solutions of the dispersion equation for surface-wave propagation evince convergence. The convergence is faster for the surface waves with larger phase speeds than for the surface waves with smaller phase speeds.

physics.optics↗

arXiv2014

Dyakonov-Tamm waves guided jointly by an ordinary, isotropic, homogeneous, dielectric material and a hyperbolic, dielectric, structurally chiral material

The planar interface of an ordinary, isotropic, homogeneous, dielectric material and a hyperbolic, dielectric, structurally chiral material can support the propagation of one or multiple Dyakonov-Tamm waves, at a specified frequency and along a specified direction in the interface plane. When multiple Dyakonov-Tamm waves can exist, they differ in phase speed, propagation length, degree of localization to the interface, and spatial profiles of the associated electromagnetic fields. Dependence on the relative permittivity scalar of the isotropic partnering material suggests exploitation for optical sensing of analytes.

physics.optics↗

arXiv2014

Multiple surface-plasmon-polariton waves guided jointly by a metal and a hyperbolic, dielectric, structurally chiral material

The planar interface of a metal and a hyperbolic, dielectric, structurally chiral material can support the propagation of none, one, or multiple surface-plasmon-polariton (SPP) waves, at a specified frequency and along a specified direction in the interface plane. When multiple SPP waves can exist, they differ in phase speed, propagation length, degree of localization to the interface, and spatial profiles of the associated electromagnetic fields.

physics.optics↗

arXiv2013

Observation of the Dyakonov-Tamm Wave

A surface electromagnetic wave called the Dyakonov-Tamm wave has been theoretically predicted to exist at the interface of two dielectric materials at least one of which is both anisotropic and periodically nonhomogeneous. For experimental confirmation, a prism-coupled configuration was used to excite the Dyakonov-Tamm wave guided by the interface of a dense thin film of magnesium fluoride and a chiral sculptured thin film of zinc selenide. The excitation was indicated by a reflection dip (with respect to the angle of incidence in the prism-coupled configuration) that is independent of the polarization state of the incident light as well as the thicknesses of both partnering materials beyond some thresholds. Applications to optical sensing and long-range on-chip communication are expected.

physics.optics↗

arXiv2011

Grating-coupled excitation of multiple surface plasmon-polariton waves

The excitation of multiple surface-plasmon-polariton (SPP) waves of different linear polarization states and phase speeds by a surface-relief grating formed by a metal and a rugate filter, both of finite thickness, was studied theoretically, using rigorous coupled-wave-analysis. The incident plane wave can be either p or s polarized. The excitation of SPP waves is indicated by the presence of those peaks in the plots of absorbance vs. the incidence angle that are independent of the thickness of the rugate filter. The absorbance peaks representing the excitation of s-polarized SPP waves are narrower than those representing p-polarized SPP waves. Two incident plane waves propagating in different directions may excite the same SPP wave. A line source could excite several SPP waves simultaneously.

physics.optics↗

arXiv2010

Surface-plasmon-polariton wave propagation guided by a metal slab in a sculptured nematic thin film

Surface-plasmon-polariton~(SPP) wave propagation guided by a metal slab in a periodically nonhomogeneous sculptured nematic thin film~(SNTF) was studied theoretically. The morphologically significant planes of the SNTF on both sides of the metal slab could either be aligned or twisted with respect to each other. The canonical boundary-value problem was formulated, solved for SPP-wave propagation, and examined to determine the effect of slab thickness on the multiplicity and the spatial profiles of SPP waves. Decrease in slab thickness was found to result in more intense coupling of two metal/SNTF interfaces. But when the metal slab becomes thicker, the coupling between the two interfaces reduces and SPP waves localize to one of the two interfaces. The greater the coupling between the two metal/SNTF interfaces, the smaller is the phase speed.

physics.optics↗

arXiv2010

Multiple trains of same-color surface plasmon-polaritons guided by the planar interface of a metal and a sculptured nematic thin film. Part IV: Canonical problem

The canonical problem of the propagation of surface-plasmon-polariton (SPP) waves localized to the planar interface of a metal and a sculptured nematic thin film (SNTF) that is periodically nonhomogeneous along the direction normal to the interface was formulated. Solution of the dispersion equation obtained thereby confirmed the possibility of exciting multiple SPP waves of the same frequency or color. However, these SPP waves differ in phase speed, field structure, and the e-folding distance along the direction of propagation.

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