Effect of grading in refractive index profile on Kerr nonlinear optical processes in single-mode sub-wavelength diameter optical fibre using a straightforward method

Abstract

A significant effect of nature of refractive index grading in the core of sub-wavelength diameter optical fibres on their performance characteristics in single-mode region is predicted and reported, for the first time, in connection with achievement of waveguide enhancement of Kerr nonlinearity-based optical processes. The analysis is based on a straightforward approach involving Marcuse spot size formulations for single-mode graded index fibre. Our formulations and results provide useful information and insight for optimum transverse dimensions of graded index fibre together with normalized core nonlinearity coefficient corresponding to profile exponent of the power law profile and should invite attention of system designers.

Keywords:

• Spot size
• Kerr nonlinear effect
• profile exponent
• effective nonlinear coefficient
• normalized effective area
• sub-wavelength diameter optical fibre

Acknowledgement

The authors are grateful to the Center for Research in Nano Science and Nano Technology, University of Calcutta, for financial support. The first author acknowledges helpful discussion with Anup Karak, Research Fellow, University of Calcutta. The second author gratefully acknowledges University Grants Commission, Government of India, for the award of Emeritus Fellowship vide No.F.6-6/2016-2017/EMERITUS-2015-17-GEN-8507/ (SA-II), dated 1 April, 2016.