近年來，光學感測器和光學掃描器的發展受到高度重視，在這些領域中光學探測與測距技術 (Light Detection and Ranging, LiDAR) 是其中的一個重要研究方向，特別是快速掃描和積體化的 LiDAR 技術成為未來的研究重點， " LiDAR on Chip " 是目前積體化 LiDAR 的一個關鍵概念，光學相位陣列 (Optical Phased Array, OPA) 是實現此概念的一種技術，為了實現較大的光束轉向角度，需要減小陣列天線之間的間距，然而過於緊密的波導間距容易引起串擾現象 (Crosstalk)，因此本論文將深入探討不同線寬的波導如何降低耦合和相位串擾對波束成形遠場的影響。
為了解決光學相位陣列之間的耦合和串擾問題，並有效提升光學相位陣列的可視場角 (Field of View, FoV)，本論文同時將探討 FoV 與間距 (pitch)、通道數等之間的關係進行深入研究。由折射率不匹配矽線波導，加入至 16 channel 之光學相位陣列，促使波導天線間的 Crosstalk 降低，此不匹配波導的寬度為 0.5 μm 與 0.4 μm，為了要讓量測解析度提高，使用兩個週期變化，可降低Full Width at Half Maximum (FWHM) 的增加量。因此光柵週期設計分別為 0.66 μm 與 0.78 μm，在 1550-nm 波長時，可使其垂直 θ 出光角重疊於 0 度，同時藉由商業軟體 Photon Design 使用時域有限差分 (Finite-Difference Time-Domain, FDTD) 模擬，針對此結構進行深入探討，模擬顯示其 FWHM 增加約 10.53 %。其中透過不匹配的線寬，使得光柵天線間的間距，可以更為緊密達 0.75 μm 來有效地提升 OPA 在 φ 方向的 FoV 達到約 110 度，相較於傳統的同線寬波導天線陣列，可將 Side lobe 明顯降低約 10 dB，其 Side Mode Suppression Ratio (SMSR) 為 16.56 dB，並將雜訊有效抑制並集束使FWHM降低約 2 度。為了適用於二維結構，分別將波長設定在 1530 nm 及 1570 nm，垂直 θ 出光角分別在 2.98 度及 -3.03 度，其波長1530 nm時，水平 φ 方向的FoV可以達到約103度，SMSR 為 14.56 dB，FWHM 約為 3.3 度，而波長1570 nm時，水平 φ 方向的FoV可以達到約100度，SMSR 為 14.87 dB，FWHM 約為 3.7 度，其可以有效實現真正的二維掃描。
本研究在量測上，利用不匹配線寬波導之 16 channel 的 OPA 晶片，透過加入 SMSR 之基因演算法適應度，使電壓調變來修正製程誤差所帶來的相位差。在水平結果 FoV 約為 80 度，垂直掃描調變角度達約每奈米 0.101 度，在FWHM部分達到 〖2.79〗^°×〖3.8〗^°，SMSR 達到約 12.67 dB × 8.18 dB。

Recently, there has been a high emphasis on developing optical sensors and scanners. Optical detection and ranging technology, known as LiDAR (Light Detection and Ranging), is an important research direction in these fields. In particular, fast scanning and integrated LiDAR technology have become a focus of future research. "LiDAR on Chip" is a crucial concept in integrated LiDAR technology. Optical Phased Array (OPA) can be utilized to realize this concept. It is necessary to reduce the spacing between array antennas to achieve a larger beam steering angle. However, closely spaced waveguides can easily cause crosstalk phenomena. This thesis will delve into the impact of coupling and phase crosstalk on far-field beam shaping through different waveguide widths.
This thesis will explore the relationship between the field of view (FoV), pitch, and channel number in depth. The refractive index-mismatched silicon wire waveguides composed of a 16-channel optical phase array reduce the crosstalk in OPA. The widths of this mismatched waveguide are 0.5 μm and 0.4 μm, and the increase of Full Width at Half Maximum (FWHM) can be reduced using two grating periods to improve the measurement resolution. Therefore, the grating cycles are designed to be 0.66 μm and 0.78 μm, and the vertical θ angle can be 0 degrees at a 1550-nm wavelength. This structure is explored in depth using Finite-Difference Time-Domain (FDTD) simulation with the commercial Photon Design software. The simulation shows an increase in FWHM of about 10.53%. Utilizing unmatched waveguide widths allows the spacing between the grating antennas to be tightly reduced to approximately 0.75 μm, effectively enhancing the OPA's FoV in the φ direction to about 110 degrees. Compared to traditional waveguide antennas with the same width, the side lobes can be significantly reduced by approximately 10 dB, and noise can be effectively suppressed, resulting in improved beam focusing FWHM of roughly 2 degrees. For two-dimensional beam steering, the vertical angles for the 1530 nm and 1570 nm wavelengths are 2.98 and -3.03 degrees, respectively. At a 1530 nm wavelength, the horizontal φ-direction can reach approximately 103-degree FoV, with a Side-Mode Suppression Ratio (SMSR) of 14.56 dB and an FWHM of 3.3 degrees. At a wavelength of 1570 nm, the horizontal φ-direction can reach roughly 100 degrees in FoV, with an SMSR of 14.87 dB and an FWHM of 3.7 degrees. These index-mismatched silicon wires enable the effective implementation of actual two-dimensional scanning.
A 16-channel OPA chip with two unmatched width waveguides was characterized for beam steering. A genetic algorithm incorporated the SMSR with fitness matching by adjusting the phase difference caused by process errors through the applied voltages. The horizontal FoV achieved approximately 80 degrees, while the vertical scanning modulation angle reached about 0.101 degrees per nanometer. The FWHM was demonstrated at 〖2.79〗^°×〖3.8〗^°, and the SMSR achieved approximately 12.67 dB×8.18 dB.

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