我們常見的粗分波多工/解多工器（CWDM），通常在極化態操作上只針對一個極化態，故在實際應用上會有所限制。
本論文為具極化態不敏感氮化矽粗分波多工器(CWDM)晶片，主要利用氮化矽波導串接馬赫－曾德爾光學干涉架構所組成來進行元件的設計，由於氮化矽材料相對於矽材料折射率較小，矽材料的熱光係數也比氮化矽來的大，故選擇氮化矽作為波導材料，波導在對於環境溫度的變化及模態的極化態上較為不敏感。接著利用matlab所寫的最佳化程式，對整個頻譜進行最佳化，使不是元件所需操作頻帶內的串擾(crosstalk)達到最低，並找出此頻譜圖下各個同向耦合器的最佳耦合距離來進行設計。
最後在實際應用上利用邊緣耦和器(edge coupler)的設計，將該分波多工器晶片經過研磨後，與光纖陣列(fiber array)封裝形成一1x4多工光纖模組。

Common integrated coarse wavelength division multiplexers (CWDM)
usually only operate for a single polarization state. Therefore, it limits practical applications.
In this thesis, we study a polarization-insensitive integrated Si3N4 CWDM operating in the O-band, which is based on Mach-Zehnder interferometer lattice filters. The device is made of square silicon nitride waveguides. Since the refractive index of silicon nitride is smaller than that of silicon, using silicon nitride as the waveguide material is less sensitive to the polarization state of waveguide mode. Meanwhile, because the thermo-optic coefficient of silicon nitride is much smaller than that of Si, the WDM spectra are more stable regarding temperature variation. In this thesis, we use Matlab to find the optimized design of directional coupler lengths for minimizing the crosstalk between channels.
To increase the coupling efficiency, we design a two-step inverted taper for fiber coupling. The device is fabricated at Taiwan Semiconductor Research Institute (TSRI) and is packaged with fiber arrays to form an integrated Si3N4 CWDM module.
 

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