Interference of speckle patterns projected by multimode fibers

M Lomer,L Rodriguez-Cobo,F Madruga,J M Lopez-Higuera

doi:10.1117/12.2196283

Abstract

In this paper, the interference speckle patterns generated by multimode optical fibers are described. In our experience two types of interference are present, random interference between modes propagated in the fiber that give rise to speckle pattern, and not random speckle interference patterns using a Michelson interferometer generating a pattern of conventional interference. Multimode fibers using different materials and core radii have been obtained interference patterns quality characteristic reducing the effects of modal noise in fiber speckle patterns. Experimental results and their potential applications are presented.

Highlights

The Recently many research papers have focused their interest in multimode optical fibers in order to use them in future communications systems leveraging spatial degrees of freedom of the multimode fiber, this is the space-division multiplexing [1]
The light coupled into the fiber becomes propagation modes (LP modes) and random interference between modes give rise to speckle pattern
With this assembly are realized interference speckle patterns obtained in a variety of multimode fibers with core diameters of 50 μm, 62.5 μm, 240 μm and 980 μm, and gradient-index profiles and step-index

Summary

Introduction

The Recently many research papers have focused their interest in multimode optical fibers in order to use them in future communications systems leveraging spatial degrees of freedom of the multimode fiber, this is the space-division multiplexing [1]. It is well known that when a coherent beam propagates in a well-structured fibers such granular light pattern (speckle pattern) is observed at the output of the fiber [2]. The fiber speckle phenomenon is due to random interference between modes propagating with different phases and many papers have been published on this subject.

Results

Conclusion