Nonlinear multimodal interference and saturable absorption using a short graded-index multimode optical fiber

TL;DR

This paper investigates nonlinear multimodal interference and saturable absorption in a short graded-index multimode optical fiber, highlighting its potential for nonlinear switching, signal processing, and mode-locked laser applications.

Contribution

It provides a detailed analysis of nonlinear effects in a specific fiber geometry, demonstrating its suitability for advanced optical device functionalities.

Findings

Potential for nonlinear switching and signal processing.

Effective saturable absorption properties for high pulse energy lasers.

Low-loss coupling between dissimilar single-mode fibers.

Abstract

A detailed investigation of the nonlinear multimodal interference in a short graded-index multimode optical fiber is presented. The analysis is performed for a specific device geometry, where the light is coupled in and out of the multimode fiber via single-mode fibers. The same device geometry was recently used to obtain ultra-low-loss coupling between two single-mode optical fibers with very different mode-field diameters. Our results indicate the potential application of this simple geometry for nonlinear devices, such as in nonlinear switching, optical signal processing, or as saturable absorbers in mode-locked fiber lasers. Saturable absorption in this all-fiber configuration is discussed and it is shown that it provides attractive properties that can potentially be used in high pulse energy mode-locked fiber lasers.