A method of calculating the gain and the output signal based on the beam pr
opagation method and rate equations is presented. It employs the complex at
omic susceptibility in the paraxial wave equation to calculate light propag
ation in integrated optics devices. As an example, an erbium-doped waveguid
e planar splitter is analyzed. (C) 2000 society of Photo-Optical Instrument
ation Engineers. [S0091-3286(00)02502-2].