隨著高科技的蓬勃發展，物聯網、智慧城市、自動駕駛等高科技產品的出現，因應各科技的快速演變，使得資料量迅速增加，因此對於頻寬和傳輸速度要求也越來越高，最後間接就促使了第五代行動通訊技術(5th generation mobile network)的誕生。在第五代行動通訊技術中，涵蓋著三大重要的技術。分別為微型基地台(small cell)、Massive MIMO(Multi-input Multi-output)、波束成型(Beamforming)。
若使用積體光路的波束成型架構，則只需要一個由雷射打入的訊號經過modulator調變之後，再經由splitter分光即可進入光學時間延遲元件，並且可藉由調變光學時間延遲元件的延遲時間達到波束偏轉的效果。
簡而言之，5G行動通訊就像是將現有的大型基地台縮小成許多更小的基地台，而每一個小基地台，會將使用者所需要傳輸的資料迅速傳遞給使用者。不僅如此，相同面積下，可以服務更多的人。而在這當中，波束偏轉就是一個最為重要的技術。
而毫米波所能傳遞的距離相較於微波更短，而且大氣中的氣體會吸收毫米波造成較大的損耗，因此我們能藉由利用5G波束成型技術將能量集中，使訊號傳遞的距離變得更遠，與此同時也能改變對非目標裝置的干擾，藉此改善訊號的雜訊比。而毫米波天線的大小也遠小於蜂巢式網路的天線，因此可將微型機基地台附著於紅綠燈、路燈、甚至是建築物之上。而我們也可利用Massive MIMO技術所提供的自由度來提升通訊的頻寬，達到提升資料傳輸速率的效果。而在此篇論文中我的研究主軸是讓光訊號擁有定向傳送功能的「波束成型的技術」。

It is safety to say that, it seems that light is impossible to be ceased or even to be store in any medium. Owing to the issue mentioned above, I attempt to develop a kind of design base on a hybrid structure plat form, such hybrid material waveguide structure benefits the efficiency of my design, it contains silicon and silicon nitride two kinds of materials that involved a number of Mach-Zehnder interferometer (MZI) switches and Variable Optical Attenuators (VOA), through these devices, it can construct a tunable optical delay line structure which search the function of temporally trapping the optical signals. The MZI tunable delay line make the provision of digitally programmable delay tuning with a resolution among 35.7 ps by manipulating the MZI switches properly to the selected optical routing paths. Such structure presents a significant pace towards the recognition of highly reconfigurable optical signal processors with broad applications for optical communications and microwave photonics. With photonic integration technology, photonic and microwave components such as the devices mentioned above can be implemented on a photonic integrated circuit, which leads to significant reduction in the footprint, cost of the product, inter element coupling loss, packing cost, and power consumption. There exists a lot of advantages in such integrated optical system, so it is worthy for me to pay attention and work hard in my research.

Abstract...1
中文摘要...2
Acknowledgement...3
Chapter 1 Introduction...8
1.1 Motivation...8
1.2 Optical True Time Delay Line for Phase Antenna Array...9
1.3Outline of This Thesis...10
Chapter 2 Background theories...13
2.1 Optical waveguide theory...13
2.2 Multi mode interference (MMI) theory...21
2.3 Optical true time delay theory...27
Chapter 3: design and simulation results of devices...36
3.1 Multi mode interferometer (MMI)...36
3.2 Mach-Zehnder interferometer(MZI) optical switch...38
3.3 Thermal phase shifter mathematic calculation...40
3.4 Propagation loss simulation...41
3.5 Proportion of light field in silicon layer...43
3.6 MVOA loss calculation by MATLAB...44
3.7 MVOA length calculation...46
Chapter 4 : Process flow and measurement system...48
4.1 Process flow introduction...48
4.2 Fabrication process introduction...53
4.3 Measurement system introduction...62
Chapter5: Result analysis...66
5.1 MVOA analysis...66
5.2 2x2 MMI analysis...69
5.3 MZI analysis under 0V...71
5.4 delay line IR camera measurement...73
Chapter 6: Conclusion...78
6.1 Improvements and prospect...78
6.2 Reference...81

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