Study Of Theory And Technology Of Glass Optical Waveguide Power Splitter And Its Propeties

In this thesis, the research advances of glass waveguides by the ion-exchange technique are introduced in detail, and the Tl +-Na+ ions become the most important ions of all ions for waveguides. And then, the industry prospect, structure, technique target and key technique of the optical power splitter are reported, and the new-type splitter with the miniature, high-quality, array and integration is arising. So the essentiality and importance of studying glass waveguide splitters is put forward. In the theory section of the thesis, the ion-exchange process of the optical waveguide and its microcosmic mechanism are studied. The diffusing dynamics of Tl+ and Na~+ ion exchange is analyzed. The stresses created by the exchange of ions with different radii cause the refractive index change. By the experiment, the stress is related to the refractive index profile of ion-exchange waveguide, which is not used for the waveguides of the Tl~+ ion exchange in sodium glass by the Fick law (only the ionic polarizability and molar volume). In the case of thallium for sodium, the index change is induced mainly by three major physical changes: ionic polarizability, molar volume, and stress. It is determined by WKB method and best fits into the "improved" Gauss function. The mode field distribution in TE0 mode of the graded index waveguide is analyzed by means of two-dimension vector WKB method and simultaneously excited by planar light wave. When the numerical solution carried out by a computer and the light field transmission has been stable, this demonstrates that the mode of the waveguide is only related to the structure of waveguide and wavelength of light wave. The results are visual and accurate, and can be quickly obtained. They are consistent with the results obtained with analytic method. And a symmetric buried channel waveguide splitter is got by a simple method about cut-off modes. The design is introduced by utilizing the beam propagation method (BPM), which provides an example of how to create, simulate, and analyze the optical waveguide power splitter. From the symmetric and asymmetric S-junction device, a novel low loss splitter is designed. This paper shows the design project of optical power splitter, and gives the factors which lead to bending loss facility. Considered the pure bending loss, transition loss and branching loss, this paper gives the confine condition, differential coefficient condition and curvature condition, and show a new structure function, compared with sinusoid and cosine and line. The processes of design and fabrication of the glass waveguide are introduced in detail in this paper. Firstly, the windows widths of the 1×4 light path are 10μm and 20μm by BPM software, respectively. And a glass substrate (3.5×1.5×0.5cm3) is fabricated in our laboratory. Secondly, the substrate is well polished and carefully cleaned. Onto it the thin3μm titanium layer is evaporated in a high vacuum chamber. Then the S shape open window is etched by a standard photolithographic process. Thirdly, the thermal diffusion process is performed in the thallium sulphate molten bath (Tl2SO4) at a temperature 530 ℃. After the time between 10 and 20 hours, a low-loss multi-mode optical waveguide is produced. Lastly, after well polished and carefully buffed, a glass waveguide splitter, which is small, simple, stable and low loss, is accomplished.Finely, the optical experimental parameters of the waveguide splitter are tested. At 0.6328μm He–Ne laser, the index change contour profiles of the six mentioned processes are reported. The interference fringe shape of the same index profile is changed from a hemi-circular to hemi-elliptical and finely to hemi-circular curve below the surface. And the normalized diffused concentrations in the x-and y-directions of waveguide on the same axes are showed. The near-field intensity patterns of one input and four outputs of the 1×4 splitter and its light path are obtained at He–Ne laser. It results in the correlation of the index profile with the diffusion theory. In the 1.2-1.7μm wavelength region, the power shows a cross power ratio, but in 1.48-1.58μm, the cross power losses of four outputs are same, and the losses of the TE and TM are also same. A multimode waveguide is produced at 1.55μm with a coupling efficiency better than 95% (less than 0.3dB) and propagation losses lower than 0.25dB/cm. The splitting ratio is 24:25:25:26 for the TE and 25:24:25:26 for the TM polarization. So the ion-exchange technology is now the basis for telecom component. In word, by the study of theory and technology of waveguide splitter and its properties, a feasibility is managed to fabricate relatively simple and cheap, fiber-compatible, reliable, high-quality, compact, low-loss ion exchange waveguides.