A detailed variational analysis of single-mode trapezoidal index fibre to investigate its propagation characteristics involving two simple approximations of fundamental mode is presented. It is shown in respect of computation of normalized field that the single parameter variational function having Gaussian and modified Bessel variations in the core and cladding, respectively, is more accurate in comparison with the Gaussian function over a wide range of values of normalized frequency and aspect ratio. Also, it predicts the propagation characteristics, more accurately, than the Gaussian function from variational and recently reported Marcuse-type formulations. Further, in terms of such range of values, a complete formulation of variational parameter for the Gaussian-modified Bessel function is prescribed for ready reference to the system users to predict the modal field and propagation characteristics. © 2016 Informa UK Limited, trading as Taylor & Francis Group.

A K MALLICK

S SARKAR

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Detailed variational analysis of single mode trapezoidal index fiber involving two simple approximations of fundamental mode with comparison relating accurate prediction of propagation characteristics

Journal of Modern Optics

We use the splice loss measurement technique in absence and presence of angular misalignment and report a simple and accurate method to predict the unknown aspect ratio of a supplied circular core trapezoidal index single mode fiber. We, first, propose to determine the spot size of the unknown fiber from splice between two such fibers with angular misalignment. Then using a known empirical relation of power transmission coefficient and a graphical technique, we employ this spot size in splice loss between a step index and trapezoidal index fiber in absence of angular misalignment to predict the unknown aspect ratio. The method should find wide use by system developers and system users. © 2018

Optik

Prediction of unknown aspect ratio of a single mode trapezoidal index fiber using splice loss technique considering angular misalignment

Accurate knowledge of spot size, an important criterion in single-mode fiber optics, is obtained by two different optimization techniques, the well-known variational method and Marcuse formulation. The later is more accurate but cannot predict fiber parameters from given spot sizes. In this study, it is shown for the first time to the best of our knowledge that using simultaneously Marcuse relations of fiber spot sizes for single-mode graded index fibers and also variational formulation, we can more accurately and easily determine the fiber parameters for a particular normalized frequency. Then it is shown with typical example of fractional power in the core that in the case of such fibers, this synthesis of these two useful approaches can also more accurately estimate propagation characteristics of practical interest. This equivalence provides an easy and useful connection between two fundamental but disjoint approaches and should find wide use. © 2015 Taylor and Francis.

A simple and elegant technique connecting Marcuse spot size relations to variational formulations in single-mode fiber characterization

Simple and complete empirical relations are presented here to determine a normalized spot size in terms of normalized frequencies over a long range and aspect ratio of a trapezoidal index single-mode fiber considering Gaussian approximation of the fundamental mode following the Marcuse method for the first time. After verification of their validity for arbitrary values of aspect ratio and normalized frequency, we calculate various propagation characteristics viz. dispersion and splice loss by using our formulations. Upon comparison, we observe an excellent match and the validity of our results with exact values and other results available in the literature. These formulas should attract the attention of experimentalists as a simple alternative to the rigorous methods of estimating the propagation characteristics of such fibers. © 2014 Society of Photo-Optical Instrumentation Engineers.

Optical Engineering

Empirical relations to determine the normalized spot size of a single-mode trapezoidal index fiber and computation of its propagation characteristics

A rigorous, much simplified, and accurate analysis of the modal field characteristics such as propagation constants, mode power confinement, delay and dispersion characteristics of a single-mode graded-index elliptical core fiber is presented applying a variational method and super-Gaussian approximation of the fundamental modal field. Normalized propagation constants, a fundamental parameter to evaluate other modal characteristics, obtained through this method showed a greater accuracy over the entire range of practical interest in comparison with other reported methods. The effects of various aspect ratios on these characteristics are analyzed. In addition, the effect of Kerr nonlinearity on these characteristics is investigated using the reported method, and a comparison is made with the linear results. © 2009 Optical Society of America.

Applied Optics

Propagation characteristics of single-mode gradedindex elliptical core linear and nonlinear fiber using super-Gaussian approximation

We present detailed propagation characteristics of single-mode elliptical core fiber using scalar variational method with novel super-Gaussian approximation. Results obtained through this method for different aspect ratios matched excellently with those reported using other methods. © 2008 IEEE.

IEEE Photonics Technology Letters

Scalar variational analysis of fundamental mode in single-mode elliptical core fiber using super-Gaussian approximation

A novel and extremely accurate near Gaussian approximation for the fundamental mode in single-mode fibers having arbitrary index profiles is proposed and verified by the variational method. The spot size calculated from our approximation matches closely the analytical and exact numerical results for step and parabolic index fibers over a large range of values of the normalized frequency V. For the low V region where the Gaussian approximation is not accurate, our results are suitable to accurately predict the propagation characteristics of devices such as directional couplers involving evanescent field coupling. © 1996 Society of Photo-Optical Instrumentation Engineers.

Journal	Data powered by TypesetJournal of Modern Optics
Publisher	Data powered by TypesetTaylor and Francis Ltd.
ISSN	0950-0340