Nested-capillary anti-resonant silica fiber with mid-infrared transmission and low bending sensitivity at 4000 nm

TL;DR

This paper introduces a nested-capillary anti-resonant silica fiber with high mid-infrared transmission and low bending sensitivity around 4000 nm, suitable for gas laser and spectroscopy applications.

Contribution

It demonstrates a novel fiber design with enhanced bend resistance and broad mid-infrared transmission, advancing fiber technology for mid-infrared applications.

Findings

Transmission window from 3500 to 4200 nm

Bending loss of 0.5 dB/m at 4000 nm with 40 mm radius

High bend resistance in hollow-core silica fibers

Abstract

We report a silica glass nested capillary anti-resonant nodeless fiber with transmission and low bending sensitivity in the mid-infrared around 4000 nm. The fiber is characterized in terms of transmission over 1700-4200 nm wavelengths, revealing a mid-infrared 3500-4200 nm transmission window, clearly observable for a 12 m long fiber. Bending loss around 4000 nm is 0.5 dB/m measured over 3 full turns with 40 mm radius, going up to 5 dB/m for full turns with 15 mm radius. Our results provide experimental evidence of hollow-core silica fibers in which nested, anti-resonant capillaries provide high bend resistance in the mid-infrared. This is obtained for a fiber with large core diameter of over 60 um relative to around 30 um-capillaries in the cladding, which motivates its application in gas fiber lasers or fiber-based mid-infrared spectroscopy of COx or NxO analytes.