| Summary: | 碩士 === 國立臺灣科技大學 === 電子工程系 === 100 === A silicon-on-insulator platform based optical waveguides with large refractive index provides high efficiency, high quality, low cost and its fully compatible processing with the complementary metal-oxide-semiconductor (CMOS) standard process. For these reasons, it is extensively utilized for both of high-speed and low power consumption optoelectronic devices. Moreover, the large refractive index difference between silicon and silicon dioxide layers can significantly reduce the device form size to submicron scale. Therefore, the silicon wire based optical ring resonator owns the potential of the highly integrated optical circuit and easy manipulation on the free spectral range (FSR) in optical communications.
In Microwave Engineering, the electrical phased array is typically composed by numerous phase shifters. However, the photonics, offering many advantages on the compact size, large bandwidth, and fast tunability, was then made into small footprint phase shifters. In this thesis, even though the multimode interference (MMI) owns the higher propagation loss compared with the directional coupler, MMI was still utilized as the coupling function in the silicon-on-insulator (SOI) microring resonator phase shifter due to its wavelength independent spectrum. Several different lengths of optical rings, matched to FSR and quality factor were designed, fabricated, and demonstrated for phase shifting applications. Titanium was deposited on silicon wire optical ring resonator to study the variations on phase and transmission.
The theoretical power splitting ratio of MMI was 50:50. The experimental data were showing the power splitting ratios were 56:44 and 54:46, respectively, for TE and TM polarization. The thermal effect on MMI was also discussed using the deposited titanium. To fully understand the polarization dependent phase, a 0.27 birefringence of silicon wire was observed by the optical low coherence interferometer. Finally, the 350-degree phase shifting was successfully demonstrated on the optical ring resonator for microwave photonics applications.
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