In recent years, several papers have addressed the modeling of wave propaga
tion through doped optical fibers and micrometer waveguides. These devices
exhibit gain and are essential for optical processing applications.
Recently, an efficient self-consistent numerical scheme for modeling short
doped optical waveguides was published in the literature. Given an input pu
mp and signal beams, a set of three-level rate equations are solved for mod
eling the interaction between the optical waves and the active doped media.
This result is used to compute the permittivity profile accurately, which
in turn is used to compute, by means of a finite element code, the associat
ed modes for the pump and signal beams. Next, these updated beams are used
in the solution of the rate equations and so on, until a self-consistent co
nvergence is reached. However, this scheme only takes into account monomode
waveguides.
On the other contrary, in order to obtain higher gain levels, highly confin
ed modes might need to be launched-the pump in particular-and consequently,
higher order modes may be excited. In this work we extend the self-consist
ent scheme for multimode waveguides, therefore, substantially enlarging its
range of practical applications. Comparisons with other numerical schemes
and experimental results, confirm the efficiency and accuracy of our model.
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