Fabrication and characterisation of cellulose-based optical fibres

生物聚合物纤维素的许多有益特性促进了其在光电器件中的应用。本项目的目的是制造和表征纤维素基生物聚合物光纤的光波导。为此，研究了不同溶剂对再生纤维素的光学性质（透射率、吸收率、折射率分布）的影响。为此，将不同类型的纤维素溶解在相应的溶剂系统中，通过扩散过程凝结成再生纤维素膜，然后进行光学表征。除了纯纤维素，各种纤维素衍生物也进行了光学检查。基于这些光学特性，芯-包层光波导结构可以通过湿旋工艺由相应的材料产生。为此，正在开发一种湿纺设备，该设备可以从纤维素和纤维素衍生物中生产尽可能无缺陷的光波导纤维。通过化学改性来操纵纤维素的光学性质，以减少由羟基引起的泛音振荡，从而能够以有针对性的方式调节衰减曲线。除了单芯包层结构外，还将由所开发的光纤产生多芯包层结构。然后测试光纤的耐辐射性、耐温性和耐湿性。此外，使用呼吸计测试纤维的生物降解性。所制造的纤维素基生物聚合物光纤的表征包括使用扫描电子显微镜和光学显微镜的综合分析。光学性质，如光波导，通过UV/维斯和NIR光谱仪测定。结晶度通过X射线衍射测定。

The numerous beneficial properties of the biopolymer cellulose promote its use in optoelectronic devices. The aim of the present project is the fabrication and characterization of cellulose-based biopolymer optical fibers for optical waveguiding. For this purpose, the influence of different solvents on the optical properties (transmission, absorption, refractive index profile) of the regenerated cellulose is investigated. For this purpose, different cellulose types are dissolved in the respective solvent systems, coagulated via diffusion processes to regenerated cellulose films and then optically characterized. In addition to pure cellulose, various cellulose derivatives are also examined optically. Based on the optical characteristics, core-cladding optical waveguide structures can be generated from the respective materials via a wet-spinning process. For this purpose, a wet-spinning device is being developed that produces fibers for optical waveguides from cellulose and cellulose derivatives that are as defect-free as possible. The optical properties of the cellulose are manipulated by chemical modifications in order to reduce the overtone oscillations caused by the hydroxyl groups and thus to be able to adjust the attenuation curve in a targeted manner. In addition to a single core-cladding structure, multi-core-cladding structures will also be produced from the developed fibers. The optical fibers are then tested for their resistance to radiation, temperature and moisture. In addition, the fibers are tested for their biodegradability using a respirometer. The characterization of the fabricated cellulose-based biopolymer optical fibers includes comprehensive analysis using scanning electron microscopy and light microscopy. Optical properties, such as light waveguidance, are determined via UV/VIS and NIR spectrometers. Crystallinities are determined by X-ray diffraction.