Extruded Antiresonant Hollow Core Fibers for Mid-IR Laser Delivery

We report an overview of our recent progress in the design and fabrication of soft-glass based antiresonant hollow core fibers (AR-HCFs) for laser delivery in the mid-IR ( $5-11\ \mu\mathrm{m}$ ). The fibers are fabricated by extrusion and subsequent drawing, using two different glasses: tellurite (70TeO 2 -13ZnO-10BaO-7Na 2 O), and chalcogenide (IG3, Ge 30 As 13 Se 32 Te 25 ). The fabricated tellurite AR-HCFs can operate from 5 to $7\ \mu \mathrm{m}$ wavelength, and the IG3 AR-HCFs can operate further up to $11\ \mu\mathrm{m}$ wavelength. The numerical and experimental losses of the fundamental mode for the fabricated fibers are on the few dB/m level. Numerical modeling study indicates that, by improving the uniformity and shape of the capillaries, losses down to 0.1 dB/m in the mid-IR (5 to $11\ \mu\mathrm{m}$ ) should be possible, making this solution attractive for the mid-IR laser delivery, such CO, CO 2 and quantum-cascade lasers.