光方向耦合器在用戶迴路系統、區域網路、有線電視網路系統中是一不可缺少的光路元件，而平面波導法製作之切換式光方向耦合器由於具有寬頻、對光極化作用及光波長不敏感之特性，且其體積小可與積體光路結合，更是高密度分波多工(DWDM)系統中一個非常重要的一種積體光路元件。在光方向耦合波導的設計中，過去多以不同的權重函數配合結構以獲得波導參數。在一個固定寬度切換式光方向耦合器中，又以Hamming function和Blackman function兩種函數對波導設計得到最佳的串擾值分別為-29 dB和-33 dB。因此本計劃提出一個新函數稱為Modified Hamming function，初步模擬之結果可獲串擾低達-65 dB。相信將其使用在固定寬度式和漸變寬度式之耦合波導結構中應可獲得更佳的效益。本計畫將利用光波導模態耦合理論，在第一年計畫中，運用Modified Hamming function，並且建立兩種不同使用需求的波導分別為固定寬度式和漸變寬度式波導結構，分析切換式方向性耦合器沿著光傳播方向具有幾何或材質變化的結構，使用波束傳播法(beam propagation method)模擬。第二年計畫以應用為主，利用第一年所提供的設計參數進行應用設計，如：光開關、電光耦合器和熱光耦合器設計，加以優化其結構，且深入了解其干擾與頻寬議題之分析與模擬。 ; Optical directional couplers play an important role in the subscribe loop, local area network, and cable television systems. However, the switching optical directional couplers fabricated by the planar waveguide have the advantages of wide bandwidth, polarization independence and wavelength insensitivity. Besides, the coupler waveguide can combine with the integrated optics due to their compact size and will be a determinate passive device in the DWDM system. The traditional designs of coupler waveguide by different weighting functions with structures are investigated in the past few years. A constant width of waveguide for optical switching coupler obtains crosstalk of -29 and -33 dB by the Hamming and Blackman functions, respectively. We propose a new function named modified Hamming function for the waveguide design. The preliminary simulation result shows a very lows crosstalk of -65 dB. Base on the preliminary results, the constant and variable widths of waveguide will be predicted to have the better performance by the modified Hamming weighting function. The optical waveguide mode coupling theory will be applied to the optical switching coupler in this project. In the first-year project, we propose a MHF to be used in the variable and constant width of waveguides. We will analyze and simulate optical waveguide structures and the variation of coupler ratio in different boundary conditions. Furthermore, we will use the Beam Propagation Method to simulate the characteristics of crosstalk. The second-year project will use the established design waveguide parameters in the first year to extend to the applications, such as optical switching, electric-optical switching and heat-optical switching. The optimum waveguide structures, the crosstalk, and broadband issues are the main subjects in the continuing study. ; 研究期間 9708 ~ 9807
