An analytical investigation of the lightwave propagation through dielectric optical fibers with helical clads is presented with the emphasis on their field patterns. The helical clad section is effectively realized by introducing conducting windings on the core-clad boundary. Using Maxwell's equations, a rigorous analytical approach is implemented to determine the field patterns in such fibers. For simplicity, two particular values of the helix pitch angle are considered, viz. 0°and 90°. The nature of fields is presented in both the situations corresponding to different allowed values of the propagation constants and the fiber diameters. The radial distributions of fields are presented under different situations, which exhibit the patterns like spikes. The observed smooth match of the fields at the core-clad interface validates of our analytical approach. The presence of a little higher amount of field in the fiber clad section is essentially attributed to the helical windings introduced over the fiber core. Further, the existence of considerable amount of evanescent waves in such fibers opens up the possibility of their applications in optical sensing.
2. Bhattacharjee, S., V. J. Menon, and K. K. Dey, "On the cutoff conditions and power distribution in fibers of arbitrary crosssection," Can. J. Phys., Vol. 69, 612-615, 1990.
3. Dyott, R. B., "Cutoff of the first order modes in elliptical dielectric waveguide: An experimental approach ," Electron. Lett., Vol. 26, 1721-1723, 1990.
4. Choudhury, P. K., P. Khastgir, and S. P. Ojha, "Analysis of the guidance of electromagnetic waves by a deformed planar waveguide with parabolic cylindrical boundaries," J. Appl. Phys., Vol. 71, 5685-5688, 1992.
5. Sinha, S., P. Khastgir, S. P. Ojha, and P. K. Choudhury, "On electromagnetic wave propagation in an optical fiber having a core radius with a periodic axial variation," Microw. and Opt. Tech. Lett., Vol. 11, 335-339, 1996.
6. Choudhury, P. K., "Power characteristics of dielectric optical piet hein kind of waveguides," Microw. and Opt. Tech. Lett., Vol. 35, 236-240, 2002.
7. Ibrahim, A. B. M. A. and P. K. Choudhury, "Relative power distributions in omniguiding photonic band-gap fibers," Progress In Electromagnetics Research, PIER 72, 269-278, 2007.
8. Cheng, Q. and T. J. Cui, "Guided modes and continuous modes in parallel-plate waveguides excited by a line source," Journal of Electromagetic Waves and Applications, Vol. 21, 1577-1587, 2007.
9. Mei, Z. L. and F. Y. Xu, "A simple, fast and accurate method for calculating cutoff wavelengths for the dominant mode in elliptical waveguide," Journal of Electromagetic Waves and Applications, Vol. 21, 367-374, 2007.
10. Suyama, T., Y. Okuno, A. Matsushima, and M. Ohtsu, "A numerical analysis of stop band characteristics by multilayered dielectric gratings with sinusoidal profile," Progress In Electromagnetics Research B, Vol. 2, 83-102, 2008.
11. Ali, M. and S. Sanyal, "FDTD analysis of rectangular waveguide in receiving mode as EMI sensors," Progress In Electromagnetics Research B, Vol. 2, 291-303, 2008.
12. Motavali, H. and A. Rostami, "Exactly modal analysis of inhomogeneous slab waveguide using Nikiforov-Uvarov method," Journal of Electromagetic Waves and Applications, Vol. 22, 681-692, 2008.
13. Buyukaksoy, A., A. Demir, and F. Hacivelioglu, "Propagation of waves in a bifurcated cylindrical waveguide with wall impedance discontinuity," Progress In Electromagnetics Research B, Vol. 6, 295-306, 2008.
14. Engheta, N. and P. Pelet, "Modes in chirowaveguides," Opt. Lett., Vol. 14, 593-595, 1989.
15. Cory, H. and I. Rosenhouse, "Electromagnetic wave propagation along a chiral slab," IEE Proc. H, Vol. 138, 51-54, 1991.
16. Singh, K. S., P. K. Choudhury, V. Misra, P. Khastgir, and S. P. Ojha, "Field cutoffs of three-layer parabolically deformed planar chirowaveguides," J. Phys. Soc. Jpn., Vol. 62, 3778-3782, 1993.
17. Choudhury, P. K. and T. Yoshino, "Dependence of optical power confinement on core/cladding chiralities in a simple chirofiber," Microw. and Opt. Tech. Lett., Vol. 32, 359-364, 2002.
18. Choudhury, P. K. and T. Yoshino, "Characterization of the optical power confinement in a simple chirofiber," Optik, Vol. 113, 89-96, 2002.
19. Choudhury, P. K. and T. Yoshino, "TE and TM modes power transmission through liquid crystal optical fibers," Optik, Vol. 115, 49-56, 2004.
20. Nair, A. and P. K. Choudhury, "On the analysis of field patterns in chirofibers," Journal of Electromagnetic Waves and Applications, Vol. 21, 2277-2286, 2007.
21. Choudhury, P. K. and O. N. Singh, "Some multilayered and other unconventional lightguides," Electromagnetic Fields in Unconventional Materials And Structures, Chap. 8, Wiley, New York, 2000.
22. Kumar, D., P. K. Choudhury, and O. N. Singh II, "Towards the dispersion relations for dielectric optical fibers with helical windings under slow- and fast-wave considerations — A comparative analysis," Progress In Electromagnetics Research, PIER 80, 409-420, 2008.
23. Singh, U. N., O. N. Singh II, P. Khastgir, and K. K. Dey, "Dispersion characteristics of a helically cladded step-index optical fiber: An analytical study," J. Opt. Soc. Am. B, Vol. 12, 1273-1278, 1995.
24. Kumar, D. and O. N. Singh II, "Some special cases of propagation characteristics of an elliptical step-index fiber with a conducting helical winding on the core-cladding boundary — An analytical treatment," Optik, Vol. 112, 561-566, 2001.
25. Kumar, D. and O. N. Singh II, "Modal characteristic equation and dispersion curves for an elliptical step-index fiber with a conducting helical winding on the corecladding boundary — An analytical study ," J. Light. Tech., Vol. 20, 1416-1424, 2002.
26. Kumar, D. and O. N. Singh II, "An analytical study of the modal characteristics of annular step-index waveguide with elliptical cross section with two conducting helical windings on the two boundary surfaces between the guiding and the nonguiding regions," Optik, Vol. 113, 193-196, 2002.
27. Kumar, D., "A preliminary ground work for the study of the characteristic dispersion equation for a slightly elliptical sheath helix slow wave structure," Journal of Electromagnetic Waves and Applications, Vol. 18, 1033-1044, 2004.
28. Kumar, D., P. K. Choudhury, and F. A. Rahman, "Low eccentricity elliptical fibers with helical windings under slow-wave consideration — Some special cases," Optik, in press.
29. Kumar, D., P. K. Choudhury, and F. A. Rahman, "Towards the characteristic dispersion relation for step-index hyperbolic waveguide with conducting helical winding," Progress In Electromagnetics Research, PIER 71, 251-275, 2007.
30. Pierce, J. R., Travelling Wave Tubes, 229-230, D. Van Nostrand, NJ, 1950.
31. Lim, K. Y., P. K. Choudhury, and Z. Yusoff, "Chirofibers with helical windings — An analytical investigation," Optik, in press.
32. Choudhury, P. K. and O. N. Singh, "An overview of optical sensors and their applications," Frontiers in Optical Technology — Materials and Devices, P. K. Choudhury and O. N. Singh (eds.), 235-271, Nova, USA, 2007.
33. Gloge, D., "Weakly guiding fibers," Appl. Opt., Vol. 10, 2252-2258, 1971.
34. Abramowitz, A. and I. A. Stugun, Handbook of Mathematical Functions, Dover, New York, 1965.
35. Watkins, D. A., Topics in Electromagnetic Theory, 39-62, Wiley, USA, 1958.