Modified S2 imaging modal decomposition technique in Few Mode Fibers

Abstract

Precise knowledge of modal content in fibers that support diferent optical modes is important to understanding fiber properties and system performance. Several techniques have been implemented for modal content characterization in few mode fibers with the intention of identifying modes supported by these fibers. Direct modal characterization techniques have become popular for allowing a fairly accurate mode analysis as well as experimentally recover the mode amplitude and phase spatial profile. However, in some specific scenarios, certain limitations such as complete mode-recovery and resolution have to be overcome with these methods. In this paper are presented some modifications to a direct method of modal recovery that allow to remove several of those limitations. A mathematical implementation that consists of adding an external reference to the method is presented and studied, as well as the explanation of the proposed mode-recovery algorithm in detail.