Y. K. Prajapati

Modal Analysis and Dispersion Curves of a New Unconventional Bragg Waveguide Using a Very Simple Method

A theoretical modal dispersion study of a new unconventional Bragg waveguide having hypocycloidal core cross-section and surrounded by Bragg cladding layers is presented using a very simple boundary matching technique [1]. An attempt has been made to determine how the modal characteristics of a standard Bragg fiber change as its circular shape is changed to the hypocycloidal shape. It is seen that in the case of a hypocycloidal Bragg waveguide single mode guidance is possible when V ≤ 10.0 where V is the normalized frequency parameter. 192 Singh, Prajapati, and Saini

MODAL ANALYSIS AND DISPERSION CURVES OF A BRAGG FIBER HAVING ASYMMETRIC LOOP BOUNDARY

An analysis of the modal propagation characteristics of a Bragg fiber having asymmetric loop boundary is made, using a simple matrix method. The boundary condition is replaced by matrix equation andthe modal eigen value equation is obtainedunder weak guidance condition. The computed results are shown in the form of d ispersion curves andcutoff frequencies andare comparedwith the dispersion curves of a standard Bragg fiber having circular core cross section. It is seen that the proposedBragg fiber with a small number of claddings (two of four) shows comparable or even better performance than the standard Bragg fiber with respect to a few mode-guidance properties.

Thinned fibre Bragg grating as a fuel adulteration sensor : simulation and experimental study

Abstract This paper presents the implementation of a thinned fibre Bragg grating as a fuel adulteration sensor for volatile organic compounds. The proposed sensor can detect upto 10% adulteration of benzene, toluene and xylene: hydrocarbons precisely, whereas traditional methods can detect only upto 20% adulteration. The results obtained from the experiments are verified using Finite Difference Time Domain method. It is found that experimental results have very less deviation from simulation results. The proposed sensor provides us with the new possibility that may have commercial application, as well.

Modal analysis and dispersion curves of an elliptical W-type single mode fiber

In this paper, the propagation of electromagnetic waves in W-type elliptical dielectric optical fiber having various cladding layers is presented. The presented fiber has concentric core and cladding which have elliptical cross section and the refractive index of one of the inner cladding (the cladding between first clad and last clad) maximum. Using elliptic cylindrical coordinates, boundary conditions are derived and longitudinal field components for the even and odd modes are obtained. The characteristic equation for the fiber to be studied is determined by solving the Mathieu (q > 0) and the modified Mathieu functions (q < 0). In order to study the fundamental mode, the modal index m is put as m = 1. Finally, the cutoff frequencies for several lower order modes have been calculated and their dispersion characteristics are plotted. The effects of elliptical eccentricity e on the mode cutoff frequencies and mode transmissions are also addressed. The analysis shows that one can control the propagation property of optical fiber by increasing the number of inner claddings. These claddings provide additional degree of freedom to control the modes.

Effect of Metallic Adhesion Layer Thickness on Surface Roughness for Sensing Application

This letter is done to find the effect of adhesion layer on the surface plasmon resonance sensor surface. Herein, titanium is used as adhesion layer between substrate, i.e., indium tin oxide coated glass, and top layer, i.e., silver. For observing the mentioned effect, simulation, as well as experimental studies, is carried out. Characterization of the fabricated chip is performed in order to observe the surface characteristics. Roughness and its effect on sensitivity are observed at different thicknesses of the adhesion layer. Moreover, the transverse magnetic field is plotted to calculate the penetration depth in sensing medium.

Influence of Dielectric Coating on Performance of Surface Plasmon Resonance Sensor

In the present study, the nature of dielectric layer above metal layer in surface plasmon resonance sensor is investigated. The performance-defining parameters, i.e., shift in resonance angle, half width at half maximum, and minimum reflection intensity, are investigated according to the variation of refractive index (real as well as imaginary) of dielectric layer. Moreover, these parameters are investigated according to the thickness variation of the dielectric layer at different purely real as well as complex refractive index of the dielectric layer.

Effect of plasma on modal dispersion characteristics of elliptical Bragg waveguide

In this paper, the dispersion characteristics of a plasma filled elliptical Bragg waveguide is investigated. The modal characteristic equations of the proposed Bragg waveguide for both ω > ωp and ω < ωp are derived. The effects of plasma frequency, numbers of cladding layers and the eccentricity of elliptical Bragg waveguide on the dispersion characteristics are studied. The analysis shows that the introduction of plasma in the proposed waveguide allows to control the propagation of modes.

A Novel Method to Calculate Beam Width of SPR Reflectance Curve: A Comparative Analysis

In this letter, beam width of reflectance curve of SPR sensor is calculated using a novel method and compared with the existing methods, e.g., FWHM. Resolution is one of the parameters which defines the performance of SPR sensor in terms of beam width. The results show that the used novel method stands successfully for all types of reflectance curve, including typical cases where existing methods fail to calculate the beam width.

Analysis of a metal clad waveguide sensor having metamaterial as a guiding layer

Abstract In this study a metal clad waveguide sensor with a metamaterial guiding layer is analyzed. Sensitivity of the proposed sensor is derived using dispersion and Fresenal’s equations for waveguiding mode and reflection mode. While efficiently analyzing and comparing the results with the existing one, some interesting findings are achieved. It is observed that the proposed sensor shows larger cover layer sensitivity and larger adlayer sensitivity compared to the dielectric guiding layer sensor due to adsorbtive properties of metamaterial. Henceforth, it concludes that the proposed sensor shows sensitivity improvement over a dielectric guiding layer sensor.

Analytical analysis of sensitivity of optical waveguide sensor

In this article, we carried out analytical analysis of sensitivity and mode field of optical waveguide structure by use of effective index method. This structures as predicted have extended mode which could interact with the surrounding analyses in a much better way than the commonly used EWS.