In an all-optical communication system, an erbium-doped fiber amplifier performs a very significant role. The effectiveness of the operation of this kind of amplifier depends on different parameters of the amplifier. Variation of the intensities of pump and signal with distance along the radius of the fiber from the core axis is one such significant parameter. In our present case, we have studied the distribution of the intensities of both the pump and signal along the radius of the fiber in an erbium-doped dual-mode fiber amplifier for the LP11 mode. In the present case, some step-index fibers of different normalized frequencies have opted. Our study is an application of the Chebyshev technique expressing the LP11 modal field in the form of a power series. A little computation is required for the prediction of the concerned results by this technique. Results obtained from this study show an excellent match with those found by the rigorous finite element method establishing its accuracy. This study using such a user-friendly and accurate technique will be helpful to the optical engineers involved in this domain.