光學雷達(Light Detection And Ranging, LiDAR)是近幾年來熱門的感測器，其通過紅外光對周圍環境進行360度環景高精度之實時量測，通過測量主要可以得到物體各個點的距離並使用這些距離重建3D影像，這補償了傳統相機只能提供二維影像的限制，成為講究安全之電動車、先進駕駛輔助系統、工業、醫療和科學等重要感測器。
目前最常見的LiDAR主要分為飛時測距(Time of Flight, ToF)以及 調頻連續波(Frequency-Modulated Continuous-Wave, FMCW)，FMCW LiDAR不僅對檢測器靈敏度要求較低，並且擁有比ToF LiDAR更高的縱向解析度、高強度之環境雜訊耐受性以及有長距離的偵測能力等優點，但目前市售的LiDAR還是皆以ToF為主，其主要原因為FMCW LiDAR系統體積龐大且難以微縮、調頻光源之頻率高精準度以及大量的光感測器，因此使得FMCW LiDAR價位居高不下，無法在大規模生產的消費產品中使用。
為使FMCW LiDAR能在市場上擁有競爭力，本論文重點為透過FMCW感測技術，結合在矽光子基板之輔助干涉儀，通過平均相位誤差來克服傳統FMCW LiDAR系統中類比輔助干涉儀的延遲光路差過長而無法縮小到晶片等級的問題。如此將不需要昂貴之線性掃頻雷射以及使雷射調頻線性化的反饋電路，達到降低 FMCW LiDAR 系統成本之目的。因爲矽光子製程廠之製程週期過長，導致無法在畢業前得到設計之晶片，因此先以模擬說明本論文之設計方法與預期結果，並以光纖搭建相同系統以測試效果。
實驗中量測了距離、速度、振動及影像，根據實驗可知距離之絕對誤差可小於2mm，百分比誤差可達0.13%，縱向解析度可達微米等級，速度之絕對誤差可小於3mm/s，百分比誤差可達1.03%，而目前市售之ToF LiDAR 縱向解析度約為在一百公尺內絕對誤差可小於2cm，百分比誤差可達0.2%，縱向解析度約為公分或毫米等級。

LiDAR (Light Detection And Ranging) is a popular sensor in recent years. By real-time measuring the surrounding environment precisely in infrared, we can obtain information such as distance from the points of an object and reconstruct 3D images. LiDAR can compensate for the limitation of traditional cameras that can only provide 2D images and makes it an essential sensor in a safety-required field such as electric vehicle, advanced driver assistance systems (ADAS), industry, medical, and science.
At present, the most common LiDARs are mainly divided into ToF (Time of Flight) and FMCW (Frequency-Modulated Continuous-Wave). The FMCW LiDAR requires lower detector sensitivity and has the advantages of the higher longitudinal resolution, higher environmental noise tolerance, and more extended distance detection capability than ToF. However, all LiDARs on the current market are mainly ToF. The main reasons come from the large size of FMCW LiDAR systems and the difficulty of miniaturization.
Moreover, the high-frequency accuracy of the frequency-modulated light source and many light detection sensors make FMCW LiDAR too expensive to be used in mass-produced consumer products.
To make FMCW LiDAR competitive in the market, we focus on combining FMCW sensing technology and auxiliary interferometer on silicon photonic substrate. Through averaging, the phase error, the long delay, optical path difference of analogous auxiliary interferometer in conventional FMCW LiDAR system can be reduced to wafer-level. This approach will eliminate the need for expensive linear frequency sweeping laser and feedback circuits to linearize the laser tuning, thus reducing the cost of the FMCW LiDAR system. Because of the long process cycle of the silicon photonics fabrication foundry, the designed chip could not be obtained before graduation. Therefore, this paper's design method and expected results are illustrated by simulations, and the same system is built with optical fiber to test the effect.
The distance, speed, vibration, and image were measured in the experiment. The absolute error of the space was less than 2-mm with a percentage error of 0.13 %; the longitudinal resolution was up to micron level, and the total error of the speed was less than 3-mm/s with a percentage error of 1.03 %. Compared with the commercially available ToF LiDAR, the longitudinal resolution was less than 2-cm with a percentage error of 0.2 % within 100 meters. Its longitudinal resolution is about centimeter or millimeter level.

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