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Modal analysis and cutoff condition of a double-clad archimedean spiral shaped lightguide



  1. Department of Physics, Bhanmati Smarak Mahavidyalaya, Ambedkarnagar 224210, UP, India
  2. Department of Physics, University Institute of Engineering and Technology, Chhatrapati Shahu Ji Maharaj University, Kanpur 208024, UP, India
  3. Department of Physics, CASH, Mody University of Science and Technology, Lakshmangarh 332311, Sikar, Rajasthan, India
  4. Department of Physics, Banaras Hindu University, Varanasi 221005, UP, India


A simple analytical approach, based on scalar wave approximation, is employed to study the modal propagation characteristics of a new type of double-clad optical waveguide with an Archimedean spiral shaped cross-section. By using the boundary conditions under the weak-guidance approximation in appropriate orthogonal coordinates, for the proposed structure, we obtain a modal eigen value equation. By solving the equation, we plot dispersion curves and comparing these curves, numerical results based on cutoff frequencies and the number of modes, are discussed. As we increase the inner cladding width, the cutoff V-value also increases and waveguide offers a single mode up to V=13.8. An attempt has been made to compare our results obtained for doubly clad optical waveguide with a single clad waveguide having the cross - section of the same shape under similar conditions. It is noted that the double-clad Archimedean spiral waveguide provides an additional degree of freedom to control the cutoff frequencies and monomode operation, where the inner cladding width can tailor the cutoff conditions within a certain limit..


Archimedean, Waveguide, Monomode, Dispersion.

Submitted at: Dec. 9, 2016
Accepted at: Aug. 9, 2017


RAM JATAN, RAM JANMA, NARENDRA KUMAR, VIVEK SINGHd, Modal analysis and cutoff condition of a double-clad archimedean spiral shaped lightguide, Journal of Optoelectronics and Advanced Materials Vol. 19, Iss. 7-8, pp. 469-474 (2017)