本論文致力於研究絕熱工程(Adiabaticity Engineering)運用於光波導，藉由定義矽光子元件的絕熱參數，再使用絕熱工程重新分配絕熱參數的分佈。使得模態在波導中傳輸時，能量不會被激發至其他模態並保持絕熱傳播。由於絕緣層覆矽(silicon-on-insulator, SOI)結構的波導對於光的偏振態相當的敏感，因此需要極化分光器(polarization beam splitters)與極化旋轉器(polarization rotators)等元件來處理不同偏振態的光訊號。由於這些元件會增加積體光路的尺寸以及損耗等問題，偏振獨立(polarization-independent)的元件變得相當重要。
根據3-dB線性分光器基於絕緣層覆矽帶狀波導的設計與模擬結果，使用絕熱工程理論將波導耦合長度縮短至18.92μm、32.91μm。將傳統的線性分光器耦合長度91.41μm進行大幅度的縮短，並保持良好的頻寬與製程容忍度。在操作頻寬100nm (波長1500nm~1600nm)下分光輸出差保持在1.8 dB以下，波導寬度製程容忍度在正負20 nm情況下分光輸出差保持在0.85 dB以下。

We present a short and broadband polarization-independent 3-dB coupler based on silicon-on-insulator (SOI) strip waveguide. The tapered couplers are designed using adiabaticity engineering to redistribute the adiabaticity over the length.The design shortens the coupling length of the device and makes sure that the initial excited mode energy is not coupled to other modes. Our simulations show that short couplers can be achieved at 18.92μm and 32.91μm, and the devices have high tolerance to fabrication errors, excess loss less than 1 dB, and larger than 100nm bandwidth.

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