Propagation characteristics of single mode step index linear and non-linear optical fiber involving improved Lorentzian approximation for the fundamental mode

In this paper we approximate the fundamental mode in single mode step-index linear and nonlinear optical fiber by single Lorentzian parameter within scalar variational framework with improved version of previous field. We show that it improves in performance in comparison to earlier one in wider range of V and works well in low-V region more accurately in terms of propagation constant, group delay and wave-guide dispersion.