Real Time Modal Decomposition in Few Mode Fibers by Selective Intensity Tapping

In this paper, modal decomposition in a few-mode fiber is accomplished by selectively tapping a few locations in the intensity profile. The proposed method allows direct computation of the complex modal coefficients for the first three fiber modes. For five modes, we have demonstrated that the SPGD algorithm can predict the complex modal coefficients with a best-case amplitude prediction accuracy of 99.03 %. The method utilizes only selective locations in the overall modal profile, and is therefore expected to be more efficient than the algorithms utilizing a complete intensity pattern for the decomposition.