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

Abstract

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