Simulation of Optical Fiber Amplifier Gain Using Equivalent Short Fibers
This work provides a computational speedup for simulating optical fiber amplifiers, which is useful for engineers designing fiber amplifiers, but the method is incremental and domain-specific.
The authors propose an equivalent short fiber model to accelerate simulations of optical fiber amplifiers by a factor approximately equal to the length ratio, demonstrating practical utility on ytterbium- and thulium-doped fibers.
Electromagnetic wave propagation in optical fiber amplifiers obeys Maxwell equations. Using coupled mode theory, the full Maxwell system within an optical fiber amplifier is reduced to a simpler model. The simpler model is made more efficient through a new scale model, referred to as an equivalent short fiber, which captures some of the essential characteristics of a longer fiber. The equivalent short fiber can be viewed as a fiber made using artificial (unphysical) material properties that in some sense compensates for its reduced length. The computations can be accelerated by a factor approximately equal to the ratio of the original length to the reduced length of the equivalent fiber. Computations using models of two commercially available fibers -- one doped with ytterbium, and the other with thulium -- show the practical utility of the concept. Extensive numerical studies are conducted to assess when the equivalent short fiber model is useful and when it is not.