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 - TY - JOUR A1 - Tarabrin, Mikhail K. A1 - Bushunov, Andrey A. A1 - Teslenko, Andrei A. A1 - Sakharova, Tatiana A1 - Hinkel, Jonas A1 - Usenov, Iskander A1 - Döhler, Torsten A1 - Geißler, Ute A1 - Artyushenko, Viacheslav A1 - Lazarev, Vladimir A. T1 - Fabrication of an antireflection microstructure on AgClBr polycrystalline fiber by single pulse femtosecond laser ablation JF - Optical Materials Express N2 - Polycrystalline infrared (PIR) fibers are used for numerous applications, one of those being power delivery for CO2 lasers. However, the fiber tip surface's transmittance cannot be increased with conventional antireflection coatings due to the surface unevenness. Antireflection microstructures (ARMs) offer an alternative way of increasing transmittance. In this work, ARMs were fabricated on the fiber tip surface of an AgClBr fiber by single-pulse femtosecond laser ablation. A single-surface transmittance of 92.8% at 10.6 μm, a CO2 laser operation wavelength, was achieved. The proposed method can help significantly improve the systems' efficiency, where power delivery for CO2 lasers or sources operating in the wide wavelength range is required. Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-15384 VL - 11 IS - 2 SP - 487 EP - 496 PB - Optical Society of America ER -