Detailed Characterization of Optical Fibers by Combining $\bm S^{\bf 2}$ Imaging With Correlation Filter Mode Analysis

Abstract

Spatially and spectrally resolved imaging (S <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> imaging) and correlation filter technique (CFT) are two very different, widespread fiber mode analysis techniques. Both techniques have been successfully employed to decompose few-modes and multimode beams respectively. In this study, we present a novel experimental tool combining S <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> imaging and CFT mode analyses in a unique system. We demonstrate that both methods are complementary with the ability to fully resolve scalar and vector-valued transverse modal fields. Using results from the combined experiment, mode powers (ρ <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) evaluated from CFT analysis and S <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> imaging are directly compared for a wide range of fiber beams (from single- to multi-mode). As a result, we experimentally identify the mode detection limit of each mode analysis and prove that S <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> imaging accuracy range can be considerably increased employing an analytical mode evaluation method. The conclusion contains a table summarizing the expertise of each mode analysis.