隨著車輛上的駕駛輔助系統和自動駕駛等功能逐漸普及，車用光學雷達的需求與研究也日漸增加。其中光束掃描是光學雷達應用的關鍵技術，而利用矽光子相位陣列即可實現低功耗、微型化和高解析度的光束掃描需求，在實現固態光學雷達的領域中扮演著關鍵技術的角色。
在本論文中，我們首先利用台積電(TSMC)所提供的D35多項目晶圓(multi-project wafer, MPW)服務，設計了一種新型轉接板，封裝多種OPA晶片和驅動電路。轉接板作為小型化電路板用途，用於連接不同尺寸、高度的光子、電子晶片，並優化晶片上的數百條導線連接問題。和現有的龐大電路板設計相比，該轉接板降低了串聯電阻問題，並提升了性能表現。
在本篇論文中我們也重點分析和量測兩種不同類型的OPA，一種是具有光學開關的16x64高密度光學相位陣列設計，另一種則為新型的串聯光學天線結構，其特色為不使用分光器便將輸入光分配到所有的光學天線中。上述晶片皆使用比利時微電子研究中心(IMEC)的多項目晶圓服務，使用標準SOI平台製造OPA，而所有量測皆使用自製的控制軟體執行。
高密度16x64光學相位陣列設計主要目的為通過四級1x2的光學開關將光分別引導到具有不同光束轉向角範圍的不同子OPA來實現廣角的光束轉向，測量並驗證切換電壓在4.2V以內的各項表現，幾乎所有開關切換都可在3V以內順利完成，也發現當使用的電極數越多，晶片受到熱串擾效應會越嚴重。此外，晶片遠場的量測得到比模擬結果更大的掃描範圍。
由於大型光學相位天線陣列會有因製程而導致的相位誤差問題，所以需要借助複雜的控制電路來校正其表現，為了克服上述問題，我們使用了一種串聯OPA設計，目的為改善由製程引起的相位誤差並降低為了控制光束的電路複雜性。該設計採用串聯方式的原因為藉由降低結構內部的光柵衍射效率，實現小發散角的發射均勻性，以此代替一般天線陣列的並行排列方式，並通過單純的波長調諧方式實現基本的二維方向控制。在遠場的量測結果中，主峰彼此相鄰2.45度，而在掃描頻譜中，可觀察到天線衍射出光維持高度的穩定性。

With the wide-spreading applications of driver assistance systems and autonomous vehicles, the demands and research on automotive LiDAR are fast increasing. Beam steering is the key function for LiDAR technology. Silicon photonics based optical phase arrays (OPAs) play important roles in realizing solid-state LiDARs due to their low power consumption, compact size, and high-resolution beam scanning capability.
In this thesis, we first design an interposer board by using the D35 multi-project wafer (MPW) service offered by TSMC to package the OPA chip and the driving circuits. The interposer board serves as a miniaturized circuit board to connect hundreds of wire connections between the electrodes on different photonic and electronic chips of different sizes and heights. This reduces the series resistance and improves the tuning performance by comparing to the prior bulky circuit board.
In addition, we focus on analysis and measurement of two different types of OPAs: one is high-density 16x64 large-scale OPA with optical switches; and the other is a new cascaded optical antenna structure without using optical splitters to distribute the input light to all optical antennas. The OPAs were successfully fabricated with standard silicon-on-insulator (SOI) platform by using the IMEC MPW service. All measurements are conducted with self-made control software.
Large-scale silicon photonics integrated 16x64 optical phase arrays (OPAs) are designed to achieve wide-angle beam steering by using four stages of 1x2 optical switches to direct the light to different groups of OPAs, each covers different ranges of beam steering angles. The measurement verifies the switching to different sub-OPAs with an applied voltage < 4.2. Almost all switching work can be completed smoothly within 3V, and we also found that when the number of electrodes used is increased, the thermal crosstalk effect of the chip will be more serious. We also obtained a larger scanning range than the simulation results in the far-field measurement of the chip.
The cascaded OPAs are designed to reduce the complexity of control circuits for steering the beam and correcting the phase errors caused by the fabrication fluctuation. The design uses a series connection of optical antennas which allow to achieve 2-dimensional beam steering with purely wavelength tuning. Instead of the single arrangement of the general antenna array to achieve emission uniformity across multiple grating antennas, multimode optical antenna array is adopted to reduce the grating diffraction efficiency and to achieve uniform emission patterns with small divergent angles. In the far-field measurement results, the main peaks are spaced by 2.45 degrees. In the beam steering measurement, stable light diffraction can be clearly observed.

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