此篇論文將研究波導的大小以及應力所造成矽線波導雙折射的影響. 在數值FIMMWAVE軟體模擬中, 矽線波導中的氧化層厚度固定為為3微米而矽厚度固定為0.25微米, 同時將有三種參數將被探討: 上包覆層厚度, 熱效應與波導雙折射效應. 將頂層的氧化層厚度變成0.05微米到1微米以看應力影響，而溫度變化也增加熱能壓力對波導效應, 同時也將波導寬度core dimension變化0.2微米到0.3微米以研究雙折射值的反應。
計算結果也證明了修改頂部氧化層厚度(0.05 µm 到 0.3 µm)時, 對雙折射有顯著的改變，但厚度超過0.3 µm變化就不太明顯。厚度範圍在0.05 µm 到 0.3 µm時, 雙折射有著比頂層氧化層更強的敏感度。但對於熱能應力變化敏感度卻不甚好，而更厚的氧化cladding層, 雖然敏感度不好, 但對於熱能應力變化卻有著不錯的敏感度。將core dimension的變化加入模擬, 我們可以得知其對雙折射的影響距甚。此0.25 x 0.25 µm2的波導core dimension有著相當低的雙折射差-0.00240。

Birefringence in the silicon waveguide can affect the performance of the silicon waveguide by causing the polarization mode dispersion (PMD), polarization dependent loss (PDL), and wavelength shifting. This drives the need to study the birefringence in the silicon waveguide and the waveguide parameters effect.
The birefringence in the silicon waveguide has been theoretically and numerically investigated. The numerical investigation was performed to the waveguide with the fixed lower oxide thickness of 3 µm by using FIMMWAVE commercial software. There were three parameters to be studied in this research, top cladding thickness, process temperature, and core dimension variation. In order to illustrate the stress effect caused by thickness, the upper oxide thickness was varied from 0.05 µm to 1 µm while the thermal stress was manipulated by varying the changed process temperature. The core height variation of 0.2, 0.25, and 0.3 µm. The core width was varied from 0.2 to µm to 0.45 µm to show the birefringence profile. Then, those parameters varied simultaneously to get the birefringence profile of the combination effect.
For the top cladding effect, the process temperature was set at 300oC and core dimension was fixed at 0.45 x 0.25 µm2. Based on the numerical investigation, the top cladding thickness variation would significantly change the birefringence in the thickness range of 0.05 µm – 0.3 µm and then kept insignificantly in the thickness over 0.3 µm. The birefringence changed proportionally as the change of stress. To observe the effect of core dimension variation, the top oxide cladding thickness was fixed at 1 µm and the cooling process temperature was fixed at 300oC. For the silicon waveguide core thickness of 0.25 µm, the wider silicon waveguide caused the large birefringence. Then, the coupled effect of top cladding thickness variation and core width variation was also observed. The result showed that the waveguide with the core dimension of 0.25 x 0.25 µm2 and top cladding thickness of 1 µm had the lowest birefringence. Finally, the waveguide core dimension and top cladding thickness variation can be utilized to get the lowest birefringence, -0.0024. In summary, the waveguide core dimension and top cladding thickness could be manipulated to tune the birefringence in a silicon wire waveguide.

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