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它在光电器件中的应用。本项目的目的是制备和表征用于光波导的纤维素基生物聚合物光纤。为此，研究了不同溶剂对再生纤维素光学性能（透射、吸收、折射率分布）的影响。为此，不同类型的纤维素溶解在各自的溶剂体系中，通过扩散过程凝固到再生的纤维素膜，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光学检查。基于各自的光学特性，采用湿纺工艺可制备包芯光波导结构。为此目的，一种湿纺装置正在开发中，它可以用纤维素和纤维素衍生物生产出尽可能无缺陷的光波导纤维。纤维素的光学特性是通过化学修饰来控制的，以减少羟基引起的泛音振荡，从而能够有针对性地调整衰减曲线。除了单芯包层结构，多芯包层结构也将从开发的纤维中产生。然后测试光纤的抗辐射、温度和湿度。此外，使用呼吸计测试纤维的生物降解性。制备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。光学特性，如光波导，是通过紫外/可见和近红外光谱仪确定的。结晶度由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.