Ultra-large Mode Area Microstructured Core Chalcogenide Fiber Design for Mid-IR Beam Delivery

TL;DR

This paper proposes a novel chalcogenide microstructured fiber with an ultra-large mode area for mid-IR beam delivery, enabling high power handling with low loss and good beam quality.

Contribution

It introduces a new fiber design with a patterned high index core that achieves ultra-large mode areas while maintaining single mode operation in the mid-IR range.

Findings

Effective mode area up to 75000 μm² achieved

Low confinement loss and dispersion slope

Good beam quality with M² close to 1.17

Abstract

An all solid large modearea (LMA) chalcogenide based microstructured core optical fiber (MCOF) is designed and proposed for high power handling in the mid IR spectral regime, covering the entire second transparency window of the atmosphere (3 to 5 microns). The core of the proposed specialty fiber is composed of a few rings of high index rods arranged in a pattern of hexagon. Dependence of effective mode area on the pitch and radius of high index rods are studied. Ultra high effective mode area up to 75000 micron square can be achieved over this specific wavelength range while retaining its single mode characteristic. A negligible confinement loss along with a low dispersion slope (near 0.03 ps/km-nm square) and a good beam quality factor (M2 1.17) should make this LMA fiber design attractive for fabrication as a potential candidate suitable for high power, passive applications at the mid IR wavelength regime.