2017, Wojciechowska, Dorota, Herczyńska, Lucyna, Simon, Frank, Puchalski, Michał, Stawski, Dawid

The ferulic acid (FA) is a natural antioxidant, abundantly present in plants, which acts as the plant's immune system. In order to take advantage of its properties, a method has been developed, which combines antioxidant FA with bio-based biodegradable poly(lactic acid) fibers and biocompatible hydrophilic polyallylamine, enabling the production of versatile base material that could be used for active anti-inflammatory wound dressings. The fibers are first subjected to aminolysis in order to obtain amino moieties on the surface, able to react with the molecules of FA. Next, the FA was attached to the aminolyzed fibers surface with use of 1-ethyl-3–(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide. The anti-inflammatory properties of the modified fibers were assessed using 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay. Presence of FA on the fibers’ surface was investigated through X-ray photoelectron spectroscopy analysis and Folin–Ciocalteu (total phenolic content) test.

2016, Chemnitz, Mario, Schmidt, Markus A.

Optical fibers with sub-wavelength cores are promising systems for efficient nonlinear light generation. Here we reveal that the single-mode criterion represents a convenient design tool to optimize the performance of nonlinear fibers circumventing intense numerical calculations. We introduce a quasi-analytic expression for the nonlinear coefficient allowing us to investigate its behavior over a large parameter range. The study is independent of the actual value of the material nonlinearity and shows the fundamental dependencies of the nonlinear coefficient on wavelength, refractive index and core diameter, elucidated by detailed case studies of fused silica and chalcogenide tapers and hybrid fibers.

2019, Elsmann, Tino, Becker, Martin, Olusoji, Olugbenga, Unger, Sonja, Wondraczek, Katrin, Aichele, Claudia, Lindner, Florian, Schwuchow, Anka, Nold, Johannes, Rothhardt, Manfred

The photosensitivity of various cerium-doped fibers has been experimentally investigated for both excimer- and femtosecond-laser illumination. The results of single-pulse, few-pulse and multi-pulse inscription of fiber-Bragg-gratings with both laser systems and the thermal aging of those gratings demonstrated the restrictions of the conventional color center model for cerium-doped fibers. To explain the short-term stability of single-pulse gratings against long-term stability of multi-pulse gratings, an extension into a two-step-model was deduced.

2018, Chemnitz, Mario, Gaida, Christian, Gebhardt, Martin, Stutzki, Fabian, Kobelke, Jens, Tünnermann, Andreas, Limpert, Jens, Schmidt, Markus A.

We report on soliton-fission mediated infrared supercontinuum generation in liquid-core step-index fibers using highly transparent carbon chlorides (CCl4, C2Cl4). By developing models for the refractive index dispersions and nonlinear response functions, dispersion engineering and pumping with an ultrafast thulium fiber laser (300 fs) at 1.92 μm, distinct soliton fission and dispersive wave generation was observed, particularly in the case of tetrachloroethylene (C2Cl4). The measured results match simulations of both the generalized and a hybrid nonlinear Schrödinger equation, with the latter resembling the characteristics of non-instantaneous medium via a static potential term and representing a simulation tool with substantially reduced complexity. We show that C2Cl4 has the potential for observing non-instantaneous soliton dynamics along meters of liquid-core fiber opening a feasible route for directly observing hybrid soliton dynamics.

2021, Litzkendorf, Doris, Matthes, Anne, Schwuchow, Anka, Dellith, Jan, Wondraczek, Katrin, Ebendorff-Heidepriem, Heike

We report the use of the extrusion technique at highest temperatures to date (975 °C-1000 °C) for the fabrication of suspended core fibers (SCFs) from glass with molar composition 65 SiO2-20 Al2O3-15 La2O3 (SAL65). Through adjusting die design and fabrication conditions, extruded preforms for fibers with two different core sizes (1.2 µm and 3.1 µm) were successfully produced. Cross-sectional microstructure and material loss of these fibers highlight the potential of the extrusion technique for fabrication of microstructured optical fibers from glasses with high softening temperature and thus high thermal and mechanical stability. © 2020. All rights reserved.

2018, Chemnitz, Mario, Gaida, Christian, Gebhardt, Martin, Stutzki, Fabian, Kobelke, Jens, Tünnermann, Andreas, Limpert, Jens, Schmidt, Markus A.

Liquid-core fibers offer local external control over pulse dispersion due to their strong thermodynamic response, offering a new degree of freedom in accurate soliton steering for reconfigurable nonlinear light generation. Here, we show how to accurately control soliton dynamics and supercontinuum generation in carbon disulfide/silica fibers by temperature and pressure tuning, monitored via the spectral location and the onset energy of non-solitonic radiation. Simulations and phase-matching calculations based on an extended thermodynamic dispersion model of carbon disulfide confirm the experimental results, which allows us to demonstrate the potential of temperature detuning of liquid-core fibers for octave spanning recompressible supercontinuum generation in the near-infrared.