Design considerations for multi-core optical fibers in nonlinear switching and mode-locking applications

TL;DR

This paper discusses the design challenges of multi-core optical fibers for nonlinear switching and mode-locking, focusing on fabrication imperfections, coupling effects, and power requirements.

Contribution

It provides an analysis of how fabrication imperfections influence device performance and offers insights into optimizing fiber design to mitigate these effects.

Findings

Fabrication imperfections affect the propagation constants and coupling.

Reducing core separation increases coupling but raises switching power.

Fabrication errors set a limit on minimum switching power.

Abstract

We explore the practical challenges which should be addressed when designing a multi-core fiber coupler for nonlinear switching or mode-locking applications. The inevitable geometric imperfections formed in these fiber couplers during the fabrication process affect the performance characteristics of the nonlinear switching device. Fabrication uncertainties are tolerable as long as the changes they impose on the propagation constant of the modes are smaller than the linear coupling between the cores. It is possible to reduce the effect of the propagation constant variations by bringing the cores closer to each other, hence, increasing the coupling. However, higher coupling translates into a higher switching power which may not be desirable in some practical situations. Therefore, fabrication errors limit the minimum achievable switching power in nonlinear couplers.