Birefringence analysis of multilayer leaky cladding optical fibre

TL;DR

This paper uses finite element analysis to study how multilayer leaky cladding affects birefringence and bending loss in different optical fibre structures, aiding design for high-power and dispersion applications.

Contribution

It provides a detailed analysis of MLC effects on birefringence and bending loss in both large-mode-area and elliptical small-core fibres, highlighting design benefits.

Findings

MLC strongly suppresses higher order modes in large-mode-area fibres.

MLC results in negligible birefringence in large-mode-area fibres.

MLC reduces birefringence in elliptical small-core fibres.

Abstract

We analyse a multilayer leaky cladding (MLC) fibre using the finite element method and study the effect of the MLC on the bending loss and birefringence of two types of structures: (i) a circular core large-mode-area structure and (ii) an elliptical-small-core structure. In a large-mode-area structure, we verify that the multilayer leaky cladding strongly discriminates against higher order modes to achieve single-mode operation, the fibre shows negligible birefringence, and the bending loss of the fibre is low for bending radii larger than 10 cm. In the elliptical-small-core structure we show that the MLC reduces the birefringence of the fibre. This prevents the structure from becoming birefringent in case of any departures from circular geometry. The study should be useful in the designs of MLC fibres for various applications including high power amplifiers, gain flattening of fibre amplifiers and dispersion compensation.