Fabrication and Characterization of Benzocyclobutene Optical Waveguide Devices by UV Illumination
| Autor: | Liang-Yin Chen, 陳亮吟 |
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| Rok vydání: | 2007 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 95 In this dissertation, buried-type benzocyclobutene (BCB) optical waveguides and devices fabricated by ultraviolet (UV) pulsed-laser illumination are investigated, particularly in the fabrication process, waveguide characteristics, material analysis, and advantages of related applications for the first time. UV pulsed-laser illumination is used to change the refractive index of BCB for optical waveguide fabrication due to its unique optical properties. Experimental results show the proposed fabrication process is greatly simplified as compared to that of the conventional method. The measured refractive index change of BCB can be varied from 1x10-3 to 4x10-3 by controlling the number of laser shots. The measured propagation loss is 0.6 dB/cm and the refractive index distribution is step-like, which is verified by the inverse Wentzel-Kramers-Brillouin method. As the fabrication is adjustable, single-mode waveguides with different mode sizes can be tailored for efficient coupling. Furthermore, chemical properties of surface damage threshold, root mean square roughness, changes of chemical functional groups, and changes of atom percentages are characterized by scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy for the analysis of the chemical mechanism behind the UV-illumination and the process parameters suitable for the fabrication of waveguides. For practical applications, directional couplers with coupling lengths of 2073 µm and 2502 µm are successfully fabricated. Compared to the simulated results, the measured coupling lengths have a minimum error of 0.2%. With the controllable refractive index, a wide range of output power ratio can be achieved, which is much more flexible for the fabrication of directional couplers. Moreover, 1×2 multimode interference power splitters are also fabricated. The best device has a refractive index change of 3.3×10-3 and an interaction length of 850 µm, which exhibits a transmission of as high as 92.03% and an imbalance of only 0.06 dB. Various integrated optical devices can be fabricated by the proposed method, which will be of great interest for future study. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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