Abstract
The problem of excitation of an optical fiber at normal incidence by a Gaussian beam is investigated. The authors have investigated two cases: (1) Neglecting the reflection from the end of the fiber, the guided modal powers and the radiated power are calculated. For the case of a truncated plane wave normally incident at the end of the rod, the modal powers are calculated and the results are compared with those of other authors using asymptotic analysis. Satisfactory agreement is found between the two. (2) The contribution of the reflection from the end of the rod is included in the analysis and the simultaneous set of equations obtained is solved numerically for the reflected, guided and radiated modal coefficients and their corresponding powers. The results, which were found to conform with the previous case, are considered satisfactory.