A simple method for study of effect of Kerr nonlinearity on effective core area, index of refraction and fractional modal power through the core of monomode graded index fibre

Abstract

Using the simple power series expression for fundamental modal field derived by Chebyshev technique, we present investigation of some important propagation parameters like effective core area, index of refraction and fractional modal power guided through the core of single-mode graded index fibre in presence of Kerr nonlinearity. In absence of nonlinearity, the said power series expression leads to prescription of analytical expressions of the concerned propagation parameters. Employing those analytical expressions, we apply iterative method in order to evaluate the said parameters in presence of Kerr nonlinearity. Choosing some typical single-mode step and parabolic index fibres for our study, we verify that the results obtained by our simple formalism match excellently with the exact results which are obtainable by applying rigorous finite element technique. This excellent agreement attests to the accuracy of our formalism. Further, our formalism requires little computation in the context of evaluation of the said parameters. Accordingly, our formalism can be considered as a simple but accurate alternative to the existing complicated methods available in literature. Thus, this user-friendly but accurate formalism will benefit the system engineers in respect of selection of suitable fibre in which modal noise due to nonlinearity is minimum.