Fiber Preparation And Modification Of Periodic Microstructures

Three dimensional periodical structures composed of dielectric materials possess a photonic band gap while two dimensional periodic metal/dielectric materials can support the surface plasmon polariton modes, both of the two kinds of periodic structures with unique optical properties can be the good candidate for biological and chemical sensors with miniature size. In this thesis, we proposed to assemble opal, inverse opal, and composite photonic crystals on optical fiber end facets to form a platform to realize practical sensing applications and some other. The prposed scheme may potentially form a serial of microstructure optical fiber sensors with further development. Due to the low cost but high productivity technique used in these structure fabrication, the proposed photonic crystals based optical fibers are adaptable for industry manufacture. Furthermore, two dimensional periodic metal/dielectric structures with variable morphologies and structure parameters which are formed by modification of monolayer close packed spheres can also be fabricated on end facets of optical fibers as well as their side surfaces. In addition, a method to produce high quality hollow cylindrical inverse opal films is proposed and demonstrated, which affords a possible option to fabricate inverse opal waveguides.Sol-Gel co-assembly parameters as well as morphology modification conditions of the monolayer composite Polystyrene (PS) microsphere arrays are investigated, and several two dimensional periodic arrays with different morphologies are obtained in large area with few defects. Followed by sputtering a layer of Ag film on these structures, optical reflection spectra of the two dimensional metal/dielectric structures which depend both on the Ag film thickness and the structure parameters are measured and analyzed. Moreover, dependence of reflection spectra of these structures on varied incident light angles and polarization are also investigated. Performance of island like two dimensional metal/dielectric structures which used as liquid refractive index sensor and surface enhanced Raman scattering (SERS) substrate is analyzed.Two kinds of fiber structures, optical fiber bundles and fiber-capillary structures, are designed to deposite high quality opal, inverse opal, and composite photonic crystals by self-assembly method. A home-made setup and the corresponding experiment conditions are developed to perform the experiments. As a result, after scanning electron microscope examination and optical reflection spectra testing, three kinds of photonic crystals in high quality with different length of periodicity can be formed on end facets of both optical fiber bundles and fiber-capillary structures. By analyzing the experimental data, features of reflection spectra on thickness of photonic crystal films as well as the distribution of reflection peak wavelength of fibers in a bundle are plotted, which agree well with simulation results. Moreover, relative humidity and liquid refractive index sensing performance of the three kinds photonic crystal films were demonstrated.Monolayer of close packed PS microsphere arrays and composite PS microspheres films are deposited on optical fiber end facets and their side surfaces by vertical assembly and sol-gel co-assembly method with modified experimntal parameters. A layer of two dimensional periodic Ag film is deposited on fiber end facets by using monolayer PS microsphere arrays as deposition mask. Similarly, according to the above mentioned fabrication technique, two dimensional periodic metal/dielectric structures with different morphologies are also produced on optical fiber end facets and their side surfaces.High quality hollow cylindrical inverse opal films produced on outer and inner surface of a capillary by sol-gel co-assembly method is demonstrated. Optical transmission spectra in different positions along the cylindrical axial directions were measured. Also, an inverse opal column embedded in a capillary was fabricated, and its inner structure as well as the optical reflection spectra perpendicular to its top and side surface was explored.