Browsing by Author "Y. Prajapati"

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Analysis of dispersion relation of the elliptical dielectric waveguides having M-type refractive index profile
(2013) Y. Prajapati; Vivek Singh; J.P. Saini
The propagation of electromagnetic wave in elliptical waveguide having M-type refractive index profiles is investigated. The considered waveguide consists of an elliptical core which lies between inner cladding region and outer cladding region and it is known as annular waveguide. The possible modes for this structure are numerically calculated by solving a dispersion relation, which is expressed in terms of Mathieu functions. The finding results of this waveguide are compared with another similar waveguide having inner cladding regions filled with air. It is observed that the cutoff V-values shifted toward lower frequency when the inner cladding region is filled with air. © 2012 Elsevier GmbH.
Analytical solution of the scalar wave equation for slightly deformed optical Bragg waveguide
(2013) Y. Prajapati; J.P. Saini; D.S. Chauhan; Vivek Singh
Using a simple analytical method, we study the electromagnetic-wave propagation in an optical Bragg waveguide which is slightly deformed at one side. We show the results of computations in the form of dispersion curves and provide a comparison with standard circular Bragg waveguides and step-index circular waveguides. We show that the correspondence between the cutoff V values for the standard step-index fiber and the new Bragg waveguide, which is slightly flattened on one side, is quite close for the lowest mode under the weak guidance condition. © 2013 Springer Science+Business Media New York.
Computing Eigen value equation and modal dispersion characteristics of an elliptical Bragg waveguide
(Urban und Fischer Verlag Jena, 2014) Y. Prajapati; Vivek Singh; J.P. Saini
Using the method of separation of variables in the elliptical coordinate system, a recursive formula for the electromagnetic fields in a new type of Bragg waveguide having elliptical core cross section with multilayered cladding is derived. The eigen equation is written in the form of Mathieu and the modified Mathieu functions and a dispersion relation is obtained for various modes supported by the proposed Bragg waveguide. The cutoff frequencies for several lower order even-odd modes have been calculated and their propagation characteristics are plotted. The results show that the dispersion curves are discontinuous and modes can exist only in particular wavelength bands. The effects of elliptical eccentricity on the mode cutoff values and mode transmission are addressed. Finally, the modal birefringence in the said waveguide is also estimated. © 2014 Elsevier GmbH. All rights reserved.
Effect of plasma on modal dispersion characteristics of elliptical Bragg waveguide
(De Gruyter Open Ltd, 2014) Y. Prajapati; J.P. Saini; D.S. Chauhan; V. Singh
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. © 2014 Versita Warsaw and Springer-Verlag Wien.
Modal analysis and dispersion curves of a Bragg fiber having asymmetric loop boundary
(Electromagnetics Academy, 2008) Y. Prajapati; V. Singh; J.P. Saini
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 and the modal eigen value equation is obtained under weak guidance condition. The computed results are shown in the form of dispersion curves and cutoff frequencies and are compared with the dispersion curves of a standard Bragg fiber having circular core cross section. It is seen that the proposed Bragg 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.
Modal analysis and dispersion curves of a new unconventional Bragg waveguide using a very simple method
(Electromagnetics Academy, 2006) V. Singh; Y. Prajapati; J.P. Saini
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.
Modal analysis and dispersion curves of an elliptical W-type single mode fiber
(Maik Nauka-Interperiodica Publishing, 2015) Y. Prajapati; Jitendra Bahadur Maurya; Vivek Singh; J.P. Saini
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. © 2015, Pleiades Publishing, Ltd.
Modal analysis of a super-elliptical Bragg waveguide with a small number of periodic cladding layers based on a very simple analytical technology
(2009) Y. Prajapati; Vivek Singh; J.P. Saini
Using a simple matrix method and replacing the boundary condition by a matrix equation, the characteristic equation of an unconventional Bragg waveguide, namely a super-elliptical Bragg waveguide, has been obtained analytically. Computed results are shown in the form of dispersion curves and are compared with the dispersion curves of a standard step index fiber and a standard Bragg fiber having circular core [V. Singh, B. Prasad, S.P. Ojha. Analysis of the modal characteristics of a Bragg fiber with a small number of claddings using a very simple analytical approach, Microw. Opt. Technol. Lett. 46 (2005) 271-275 [1]]. It is seen that the correspondence between the cutoff values for the standard step index fiber and the new super-elliptical Bragg fiber is quite close for the lowest mode under the weak guidance condition. © 2007 Elsevier GmbH. All rights reserved.
Modal characteristic equation and dispersion characteristics for an elliptical Bragg waveguide with a small number of claddings
(2011) Y. Prajapati; Vivek Singh; J.P. Saini
This article presents a rigorous analytical treatment of electromagnetic wave propagation in a new type of Bragg waveguide having elliptical core cross-section surrounded by Bragg cladding layers. Using Maxwell's equations in elliptical coordinates, the field components are obtained that specially incorporate Mathieu (q > 0) and the modified Mathieu functions (q < 0). Using this equation the modal dispersion curves for even guided modes are obtained and plotted for different cladding eccentricity e. It is found that the dispersion curves are discontinuous and modes can exist only in particular wavelength bands. Finally, the modal birefringence in the said waveguide is also estimated. © 2011 Wiley Periodicals, Inc.