Hydrothermal Growth And Optical Fiber Sensing Of Zinc Oxide Nanowires

ZnO nanowires have been recognized as a kind of extremely important materials in a broad range of high-technology applications, such as biology, medicine, chemistry, semiconductor industry, sensor technology, nano science and technology. Specially, ZnO nanowires in highly oriented and ordered arrays have been demonstrated to be important for optical fiber sensing applications. Various fabrication techniques have been established for growing ZnO nanowires. But hydrothermal growth method is energy-efficient and inexpensive to form massive high-quality ZnO nanowires, since it avoids using high temperature and complex vacuum environment instruments, and that it is more friendly to environment, inexpensive, high reliabe, more flexible. In this paper, bases on the used research at home and abroad, we proposed a promising hydrothermal method to growth of well-arrayed, large-scale ZnO nanowires on optical fiber devices. The spectral characteristics and sensing characteristics of these optical fiber devices covered by ZnO nanowires are studied in detail, and some innovative results were achieved. The main work is summarized as follows:1. Based on the used hydrothermal method, we proposed to the operation of ZnO nanowires growth on optical fiber devices: 1) optical fiber devices fixed by the mold made of by teflon and polydimethylsiloxane(PDMS) to avoid damage in the operation; 2) the steps of prepared of solution; 3) covered the seed layer on optical fiber devices by Czochralski method; 4) ZnO nanowires growth on optical fiber devices by growth solution; 5) sample cleaning operations before and after ZnO nanowires growth.2. Based on the fiber bubble, we demonstrated the fiber bubble to monitor the ZnO nanowires growth. By the spectrum, we got the growth speed was about 2 nm/min, and the fiber bubbles were isolated from outside with the 160.7 nm ZnO nanowires. A high-precision humidity box was made for optical fiber sensor. Specially, the range of relative humidity is from 10% to 95%, and the accuracy is 0.1% in this box. Tapered Long-period fiber grating covered by ZnO nanowires can be a humidity sensor. The measuring range of the device was from 10% to 95%, and the change of amplitude of resonant wavelengths near 1375 nm was nearly 20 d B, and the wavelengths shift was nearly 10 nm. The devices shows that excellent repeatability.3. Tapered long-period fiber grating covered by ZnO nanowires can be used to detect concentration of solution. Systematically, we compared the response of tapered LPFG covered by ZnO nanowires with the bare device to the several solution with different concentration. The device covered by ZnO nanowires had nearly changed 16 d B around the resonance wavelength of 1525 nm to measure the concentration from 0% to 25% of sodium chloride, calcium chloride, glucose, since the device without the ZnO nanowires had only about 2 d B changes. Compared with the bare device, the device covered by ZnO nanowires was more sensitive to refractive index from 1.33 to 1.40.4. We explored to fabricate grating and M- Z interferometer by used of single ZnO nanowire. And the hydrophilic and hydrophobic properties of ZnO nanowires can be transformed by ultraviolet light exposure and heat or dark storage. We explored to make the micro lens by used of the above property.