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標題: | 以粒子群最佳化演算法設計適用於雙極化的高效率光柵耦合器 Two-dimensional Grating Coupler Compatible with Dual Polarization Based on Particle Swarm Optimization |
作者: | 戴胤 Yin Dai |
指導教授: | 黃定洧 Ding-Wei Huang |
關鍵字: | 二維光柵耦合器,矽光子學,積體光學,粒子群最佳化演算法,兩階段蝕刻,繞射強度漸變型光柵耦合器,自動化設計, 2-D grating coupler,silicon photonics,integrated photonics,particle swarm optimization,two-step etching,apodized grating coupler,design automation, |
出版年 : | 2022 |
學位: | 碩士 |
摘要: | 在科技迅速變化的現代,元件自動化設計可以大幅縮短元件開發時程,再搭配最佳化演算法設定合理的效能指數,便可快速產出符合各式需求的元件。 本篇論文將以 python 實作包含演算法在內的完整自動化設計流程,搭配製程簡單且最小線寬為 150 nm 的二維光柵耦合器,利用最佳化演算法來調整元件參數,過程會以 Ansys 公司的商用軟體Lumerical-FDTD 來模擬元件效能。如此一來便可同時滿足:元件自動化設計、快速設計、高效元件設計的需求,提供一種設計模式給科技迅速變化的現代做為參考。 為了提高二維光柵耦合器的耦合效率,本篇論文使用了三種設計方法,分別為繞射強度漸變型 (Apodized) 光柵、兩階段式蝕刻、傾斜的光柵排列。除此之外,為了降低最佳化過程的 3D FDTD 模擬次數,採用了兩階段式的最佳化流程來縮小最佳化演算法的搜索範圍。並且利用三次方樣條內插法來內插出光柵的各個週期中的漸變參數,此種作法可減少元件的參數數量,藉此維持最佳化演算法的求解能力。 本二維光柵耦合器為設計於 C-band,於 1550 nm 處針對極化方向平行於入射面的 P 極化有最高理論耦合效率為 48% (–3.2 dB),極化相依損耗為 0.17 dB。–3 dB 帶寬為 40 nm,兩方向波導之串擾 (Crosstalk) 在 100 nm 的帶寬中皆小於 –15 dB。 最後會與其他文獻設計出的二維光柵耦合器做比較,–3.2 dB 的元件耦合效率已足以證明此篇自動化、最佳化、快速設計流程的有效性。且鑒於本篇光柵耦合器並無使用金屬反射層等複雜結構,並最小蝕刻線寬 (Minimum Feature Size) 為 150 nm 的全蝕刻,單純的結構亦有利於製造量產。若未來需要考量其他項元件效能,做多目標式的元件設計,我們也只需將效能指數設為多目標函數,並沿用此種設計流程,便可快速設計出各式需求的元件。 As the technology changes rapidly nowadays, design automation can shorten the development time of device significantly. With the optimization algorithm by setting a proper figure of merit, we can develop various devices to meet different needs. In this thesis, the design automation and optimization algorithm were implemented in Python. A design pattern of 2-D grating coupler which was easy to be fabricated, under the limitation of 150 nm minimum feature size, was applied with the commercial CAD software, Lumerical FDTD Solution from Ansys. Based on the design pattern, we can achieve automated design, fast development, device with high performance, to meet the technical needs today. The 2-D grating coupler combined three design ideas: diffracting apodization, two step etching, and tilt grating lattice. In addition, the design flow was split into two steps so as to narrow the searching space of optimization algorithm and reduce the times of 3-D FDTD simulation. Furthermore, the number of parameters can be reduced and the searching ability of optimization algorithm can be sustained by applying the cubic spline interpolation to the parameters of apodized 2-D grating coupler. The 2-D grating coupler is designed for C-band, and the performances of the optimized designed are: the incident light which electric field polarized parallel to its incident plane has peak of theoretical coupling efficiency is 48% (–3.2 dB) at wavelength equals to 1550 nm; polarization dependent loss is 0.17 dB; the –3 dB bandwidth is 40 nm; and the crosstalk between two waveguides is smaller than –15 dB between 100 nm bandwidth. At the end of this thesis, the 2-D grating coupler was compared to the others, and the theoretical coupling efficiency is as high as –3.2 dB could validate the performance of the two steps design flow and the design automation in this thesis. Since the grating coupler is designed without complex structures like metal mirror, and the minimum feature size is 150 nm, it could meet the requirement for mass production. Also, it’s possible to develop various devices for more complex needs by the multiple-objective optimization and the design flow in this thesis. We just need to make figure of merit as a function of the multiple objects. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/86514 |
DOI: | 10.6342/NTU202202316 |
全文授權: | 同意授權(全球公開) |
電子全文公開日期: | 2023-08-31 |
顯示於系所單位: | 光電工程學研究所 |
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