TY - JOUR A1 - Adomavičiũtė-Grabusovė, Sonata A1 - Hinkel, Jonas A1 - Usenov, Iskander A1 - Novikov, Alexander S. A1 - Sakharova, Tatiana A1 - Döhler, Torsten A1 - Geißler, Ute A1 - Feliksberger, Elena A1 - Artyushenko, Viacheslav T1 - Microstructuring of the end-surface for silver halide polycrystalline fibers to suppress Fresnel reflection JF - Optical Materials Express N2 - Silver halide polycrystalline infrared fibers (PIR) have unique properties such as excellent transmittance in the spectral range from 3 to 17 µm, while also being highly flexible, non-toxic, and non-hygroscopic. They are used in industry and medicine for CO2-laser power delivery, flexible infrared imaging, and remote process spectroscopy. While PIR fibers possess a quite low attenuation (0.1-0.5 dB/m) in the 8-12 µm range, their total transmittance is limited by significant Fresnel reflections at the fiber end faces due to the high refractive index of silver halide (>2.1). Functionalization of these surfaces with specially designed Anti-Reflective Microstructures (ARMs) enables a striking enhancement of fiber transmittance. In this work, direct imprinting (or embossing) of microstructures to fiber ends and their profiling with a microstructured knife was applied to fabricate such ARMs. The resulting two-dimensional Moth-eye microstructures and one-dimensional microgrooves at the PIR-fiber ends enable to an increase of fiber transmittance in a broadband range of (5-17 µm) as well as to reach up to 20% improvement for PIR-fiber laser cables used for power delivery of CO2-lasers at 10.6 µm. KW - effective refractive index KW - fresnel reflection KW - infrared fiber KW - infrared imaging KW - quantum cascade semiconductor laser KW - refractive index Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-15549 VL - 12 IS - 1 SP - 34 EP - 48 PB - Optica Publishing Group ER -