Modes in divergent parabolic graded-index optical fibers

The authors discuss an optical fiber characterized by a core of divergent parabolic graded-index profile. A general formulation is developed to study this fiber as well as other types, including standard step-index and convergent parabolic profiles. An analytical approach to solve the basic differential propagation equation is developed. The solution takes the form of a summation of Bessel functions. An algorithm is programmed and simulations are carried out. Main characteristics of divergent profile fibers, such as propagation constant, dispersion, and power distribution, are presented and compared to those of standard fibers. It is found that the principal mode LP₀₁ exhibits a flat top distribution that better fills core´s fiber, suggesting possible applications for laser fibers and amplifiers