| Summary: | 碩士 === 國立臺灣科技大學 === 電子工程系 === 99 === Due to the advantages of silicon material on low cost, transparency in telecommunication wavelegnths, CMOS compatible processing, and the high index contrast for a small footprint, the silicon-on-insulator (SOI) platform is utilized to offer the potential of constructing and processing photonic integrated circuits on the massive electronics fabrication infrastructure. Ring resonator has been developed for its high density and wide free spectral range (FSR), thus utilized as the multiplexer in DWDM applications. In biosensing, the resonance wavelength shift induced by the refractive index change of sugar solution cladding could be detected by the ring resonator, which owns the properties of low cost, small foot print, wider sensing region, and test paper needless, thus with the potential for commercial applications.
In this thesis, the multimode interferometer (MMI), insensitive to the wavelength and polarization, was utilized as the coupling function in microring resonator for biosensing. In lithography process, I-line stepper could easily demonstrate the ideal critical dimension of 0.5 ?慆. On the other hand, the directional coupler is requiring the E-Beam lithography to achieve the critical dimension of 0.3 ?慆 The vertical angle is above 85 degree, the sidewall roughness is less than 10 nm, and the propagation loss is characterized as 15 dB/cm.
The power splitting ratio of MMI was 50:50. The measured extinction ratio at 1550 nm wavelength and the quality factor were 12 dB and 5740, respectively. The FSR was 0.55 nm, and the phase shift was 0.12 nm while the microring resonator was cladded with 5g/dL sugar solution. If the resolution of tunable laser source is 1-pm, the detection limit could be shown as 5.72×10-5 RIU(Refractive Index Unit). The sensitivity of wavelength shift versus the glucose effective index change was 161 nm/RIU.
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