Fabrication Of Novel Special Optical Fibers And Their Applications

Various type of special optical fibers and related devices have been widely used in such fields as fiber communication, fiber sensing, biomedicine, materials processing and military technology, etc. This dissertation is directly supported by the national863high technology program China "Rare-earth (RE) doped fibers","Novel special optical fibers" and the national natural science foundation of China "The devices based on optical fiber for fine-grained Information safety net of optical circuit switching". The main achievements of the dissertation are listed as follows:1. A deep analysis of quartz glass network is done, and the transformation relationship between different crystal forms of SiO2is also discussed. Furthermore, the fabrication of porous core layer during the RE doped fiber manufacturing process is researched. It is shown that the quality of the soot layer is depend on the deposition temperature and the components of the reactants. Especially, the relationship between Er3+concentration and deposition temperature of porous layer in Bi3+-Ga3+-Al3+codoped Er3+-doped silica-based fiber is studied. And the best deposition temperature is1560-1600℃.2. A novel solution doping technique called "online" solution doping technique is used in the RE doped fiber fabrication process. This technique has some advantages than the traditional solution doping technique, such as cost saving, reducing workloads and so on. The solution doping mechanism is analyzed in theory of surface physics and fluid mechanics. It is shown that absorption of ions in the porous layer with the process of solution soak and seepage in the porous layer. Furthermore, some modified methods for reinforcing effect of the different stages are given in this paper.3. Analysis of the effect of annealing on the self-made erbium doped fiber. The experiment results show that the process of annealing can make the hydrogen loaded optical fiber get more stability, lower loss and higher efficiency for output light of lasing. A stable and single-longitudinal-mode, dual-polarization erbium doped fiber laser at room temperature with two fiber Bragg gratings directly written in a hydrogen loaded erbium doped fiber is presented, and the birefringence of erbium fiber is0.89×10-6. Furthermore, A stable and single-longitudinal-mode, single-polarization erbium doped fiber laser at room temperature with two polarization maintaining fiber Bragg gratings directly written in a polarization maintaining and photosensitive erbium doped fiber is proposed and experimentally demonstrated.4. To get large-mode-area, high absorption erbium doped fiber, a novel fiber structure with multi-core-layers which have alternating high and low refractive index is proposed. This method can be demonstrated by theoretical analysis. After several tries, a erbium doped fiber with absorption coefficient75dB/m@1530nm, mode field diameter14.5μm@1550nm is fabricated successfully.5. Coupling coefficient in symmetrical twin-core fiber (TCF) is analyzed. When1.5≤V≤2.5, other parameters are fixed, coupling coefficient increases with the increase of signal wavelength, increases with the decrease of relative refractive index difference, increases with the decrease of standard distance between two core center. A improved fabrication method of TCF is proposed. This TCF fabricated by new method can make the insert loss in0.5dB when fusion splicing with common fiber. Twin-core erbium doped fiber amplifier (TC-EDFA) can be used as a automatic gain equalization optical amplifier. This characteristics is demonstrated by theoretical analysis. A self-made TC-EDFA is used in our experiment, the results show that after the TC-EDFA, the power fluctuation decreases from input single5dB to out single3dB.6. Analysis of dispersion decrease fiber (DDF) using for optical pulse compression, in the process of adiabatic optical pulse compression, the compression efficiency depend on the group velocity dispersion(GVD) of input point and output point in the DDF. To enhance high compression efficiency, achieve high compression factor at wavelength1550nm, a fiber with quadruple-clad which has small dispersion at1550nm is analyzed and designed in this paper. After several tries, a125μm quadruple-clad fiber whose dispersion and dispersion slope at1550nm is2.1ps/(nm·km),0.125ps/(nm2·km), respectively.230m DDF is drawed by special drawing equipment, fiber diameter increases from80μm to130μm and its dispersion decreases from5.185ps/(nm·km) to0.172ps/(nm·km).