A straightforward approximate analysis of Kerr nonlinear processes in sub-wavelength diameter optical fiber with better accuracy over variational technique

• Novel technique using Marcuse method to estimate maximum Kerr nonlinear processes.
• It confirms the analytical model more accurately than variational method.
• Applicability shown in diameter optimization of subwavelength diameter optical fibers.

We report a simple and straightforward approximate analysis to investigate the effect of Kerr type nonlinear optical processes in sub-wavelength diameter step index optical fibers based on Marcuse method in single mode region. Optimum core diameters of such fibers, predicted by us, together with relevant core nonlinearity coefficient and effective area are seen to be compatible with the analytical values indicating the validity of this novel application of the elegant approximate method. However, the corresponding values, obtained by earlier variational method, show larger discrepancy with analytical findings in comparison with ours. Also, maximum enhancement of nonlinear processes within single mode region, confirming almost the analytical method, assures less diffraction. Formulations, coupled with simplicity and novelty of the present analysis, should find wide use by system users and experimentalists in this emerging area.