An Analytical Expression for the Effective Area of the Step-Index Single-Mode Optical Fiber

The nonlinear coefficient {\gamma} of the step-index single-mode fiber (SMF) is inversely proportional to the effective area of that fiber. An analytical expression for the effective area of the hybrid HE11-mode of the SMF is derived for the first time, using its exact electromagnetic field expressions. The effective area is found in terms of generalized hypergeometric functions. A simpler expression is also deduced under the weakly-guided fiber approximation, and is found to be in agreement with established theory.