Study On Fabrication Of Microscale Photonic Polymer Devices And Their Properties

Polymeric photonics, which combined the merits of polymer and principles of photonics and aimed at creation and application of polymeric photonic devices, have promoted the development of information technology. Many new polymer materials with novel optical quality have been obtained, which expanded the field of polymeric photonics. The development of polymeric photonics requires new polymer devices, especially three-dimensional devices with micro/nanoscale. Traditional lithography mainly focuses on two-dimensional fabrication, which is not suitable for fabrication of three-dimensional microstructures. The difficulty in polymer devices fabrication has limited the further development of polymeric photonics, which should be solved.In this work, we focused on the issue to improve the optical properties of dye-doped polymer, in which the fluorescence efficiency of dye molecules might be suppressed in high concentration because of aggregation. New polymer material was exploited to achieve this purpose by increasing the dispersion of dye molecules in polymer. On the basis of this, three dimensional photonic microstructures were constructed by using self-assembly and two-photon polymerization. Furthermore, the investigation on the interaction mechanism between light and these microstructures promoted the development of new polymeric photonics devices.The whole paper consists of six parts and the main point of each part is listed as following:Chapter 1: This chapter covers literatures review. Materials, devices, and fabricating method about polymeric photonics were discussed in this part. The key problems faced for polymeric photonic devices were summarized. Finally, we addressed the purpose, significance and contents of this thesis.Chapter 2: Laser dye molecules were doped into polymer to make solid state gain medium. The structure of fluorescein was modified to improve the solubility in polymer. Furthermore, carbosilane dendrimer was introduced into the gain medium. The use of allyl-FL, as well as carbosilane dendrimer impelled increasing solubility, limiting self-aggregation and intermolecular energy transfer and promising a high level of optical gain. Solid-state gain media were constructed by using allyl-FL/carbosilane dendrimer/PMMA and RhB/PMMA, respectively. These gain media will be used in microscale emiting devices.Chapter 3: This chapter is focused on the self-assembly of opal photonic crystal in optical range. Opal photonic crystal could be used as optical mirror because of its Bragg reflection light with special wavelength because of photonic bandgap. The property of opal photonic crystal can be used to investigate the interaction between light and photonic crystal structure, and fabricate microscale emitter. Resonator cavity was fabricated by sandwiching dye-doped gain medium between two opal photonic crystals.Chapter 4: This chapter demonstrated the modification of spontaneous emission of dye-doped polymer film by photonic crystal resonator cavity. Lasing action was observed in resonator cavity fabricated by allyl-fluorescein/dendrimer/PMMA and opal photonic crystal, which was explained by photonic bandgap effect in opal photonic crystal. In addition, the lasing output was observed at an unordinary angle, owing to the superprism effect of opal photonic crystals. Amplified spontaneous emission (ASE) was observed in resonator cavity fabricated by RhB/PMMA and opal photonic crystal. The ASE phenomenon was attributed to the photonic bandgap edge effect in opal photonic crystal, which was collaborated by photoluminescence lifetime experiment. The results in this chapter provided a new way for constructing opal photonic crystal laser.Chapter 5: This chapter is focused on the improving spatial resolution and constructing novel polymeric microstructures by two-photon polymerization (TPP). Firstly, the spatial resolution by TPP was investigated. Different polymeric suspended fibers were obtained by finely adjusting the laser power and exposure time. From the experimental results, not only the spatial resolution, but also the shape of the suspended fibers could be modified by changing laser power and exposure time. Secondly,"double-polymerized method"was proposed to fabricate embedded structure in epoxy. SU-8/PMMA interpenetrating network was formed by selective polymerization of MMA resin in SU-8 network by using TPP, which resulted to the embedded structure in epoxy SU-8. By doping allyl-fluorescein dye into MMA resin as probe, the embedded structure was characterized by confocal laser fluorescent microscope. This"double-polymerized method"provided new way in constructing novel microscale polymeric diffraction grating, polymeric waveguide.Chapter 6: The conclusions were drawn in this chapter and the future researches were discussed.