| 摘要: | 中文摘要
當前因無線網路技術(Wireless Fidelity, Wi-Fi)與網路終端設備的高速化，過往所常用的銅線傳輸，已無法面對大量數據與高速化傳輸狀態。因應此問題，我們藉由光纖傳輸方式來進行訊號傳輸，並且使用到矽光子技術，藉由矽光子技術來達到高頻寬、高傳輸速度與高頻寬效果，來因應大量數據傳輸之需求。而在醫療應用部分，生物檢測也有一定的應用市場，可以透過材料與結構特性來進行細胞偵測，在醫療應用上可達到方便攜帶、響應速度快等優點，而在矽光子技術的發展中。其環形共振腔(Ring Resonator)以及馬赫曾德爾干涉儀(Mach Zehnder Interferometer)皆是主要關鍵光學元件，而以上光學元件應用，又有分為線性元件與非線性元件，線性元件應用有調製器、感測器、全光開關、濾波器等，而在非線性元件應用上有波長分波多工(Wavelength Division Multiplexing)。
本論文，主要以氮化矽(Si3N4)波導製作而成的微環形共振腔耦合馬赫曾德爾干涉儀所搭配而成的結構，並對其整體結構覆蓋一層二氧化矽(SiO2)，透過薄膜加熱器於馬赫曾德爾干涉儀下臂進行熱調製，透過這樣的方式來針對環型共振腔進行濾波功能的開關動作。我們將會透過環形共振腔設計中其中一種全通濾波器(All Pass Ring)結構，來進行應用上設計，藉由全通濾波器所產生的共振峰之自由頻譜範圍，去定義出馬赫曾德爾干涉儀下臂光程差長度，並在透過加熱器所產生的熱來改變馬赫曾德爾干涉儀下臂的有效折射率，此時將會改變下臂相位，透過這樣的方式會與上臂相位產生相位差，下上臂結合後，來觀察下臂相位對於上臂全通濾波器所產生共振頻率影響，透過整合全通濾波器的自由光譜範圍FSR與MZI的FSR來進行優化設計，使濾波器能夠在過濾和擷取功能間實現切換。
第二部分主要是針對環形共振腔(Ring Resonator)及馬赫曾德爾干涉儀(Mach Zehnder Interferometer)結構先使用MATLAB將個別結構進行工作原理確認與穿透頻譜驗證，我們會先針對環型共振腔共振條件進行說明，並且分析2種環形共振腔的差別，之後開始探討環形共振腔之耦合狀態及共振的光功率比例。因本論文只使用到All Pass Ring，故我們會針對此結構之直波導進入環形波導行走一圈後的光功率損耗比〖K_p〗^2、光從直波導傳播至環型波導的光功率比〖K_e〗^2、自由頻譜(Free Spectral Range)、半峰全寬(Full Width at Half Maximum)、精緻值(Finesse)、品質因子(Quality Factor)等參數進行探討。
之後透過RSoft FemSIM軟體來進行模擬，主要是確認各別材質與結構參數下的有效折射率與群折射率以及單一橫向電波TE(Transverse electric)模態的穩定度。並將以上參數轉成單一元件方式匯出為製程設計套件(Process Design Kit, PDK)，之後再匯入OptSIM進行模擬，此方法主要是透過光子電路的方式來避免長時間模擬，並且在進行MATLAB與OptSIM模擬結果確認，再進一步去確認Ring Coupling MZI結構在這樣的串接下的模擬。
並且針對熱調製部分進行RSoft熱光效應模擬來得出其熱影響波導有效折射率的多寡。並將其模擬結果轉為製程設計套件(Process Design Kit, PDK)方式匯入OptSIM，進行不同溫度變化下於不等臂長的馬赫曾德爾干涉儀干涉結構下的相位變化，並透過光強度的變化，並確認移動的相位。
第三部分我們將透過以上的理論與手法，先透過五種結構來進行探討，探討單一馬赫曾德爾干涉儀等臂長與不等臂長差異，及環耦合等臂長與不等臂長馬赫曾德爾干涉儀結構下，其被動特性與主動調製後之特性分析，並進行兩種熱開關結構之設計，透過模擬方式來確認加熱器與波導在不同高度、不同材料下來進行熱與折射率關係，之後使用不同的臂長來針對全通濾波器之共振峰進行開關動作，以模擬方式來確認馬赫曾德爾干涉儀下臂長度是否透過熱調製方式來進行開關動作，而因應光通訊應用波長，故我們將考慮其1540nm~1560nm區間，其開關效果得呈現，並在因應光罩Layout設計與製程的通用性，進行結構面積縮小化設計，針對其波導彎曲尺寸進行FullWAVE FDTD模擬，來分析不同彎曲半徑下損耗的變化，並輔助我們去選擇使用。
第四部份進行樣品製程與實物量測架構及設備進行說明，並且針對擬合方法進行說明，首先我們將針對量測架構所使用設備進行介紹，之後我們將樣品製程分為被動元件製程說明與加熱器元件製程說明，並針對環耦合等臂長與不等臂長馬赫曾德爾干涉儀結構下實際樣品進行被動量測與主動偏壓進行模擬交叉比較，之後進行兩種熱開關結構之樣品量測分析。
最後在第五章節針對本論文被動數據與調製數據來確認調製效果，進行優化改善以及調至最佳化探討。
;ABSTRACT
With the rapid development of wireless networking technology (Wi-Fi) and the acceleration of network terminal devices, traditional copper wire transmission can no longer meet the needs for massive data throughput and high-speed transmission. In response, this thesis explores the use of optical fiber transmission supplemented by silicon photonics technology, which achieves high bandwidth and transmission speeds necessary for large-scale data transfer. Additionally, in medical applications, biosensing has a significant marKet presence. Utilizing the material and structural properties for cell detection offers advantages such as portability and rapid response, crucial in medical applications.
Silicon photonics technology, particularly the Ring Resonator and Mach-Zehnder Interferometer (MZI), are Key optical components in this research. These components are categorized into linear devices such as modulators, sensors, all-optical switches, and filters, and nonlinear devices including applications in Wavelength Division Multiplexing (WDM).
This thesis primarily focuses on a structure created from silicon nitride (Si3N4) waveguides that form micro-ring resonators coupled with Mach-Zehnder Interferometers, overlaid with a silicon dioxide (SiO2) layer. Thermo-Optic modulation is applied using thin-film heaters on the lower arm of the Mach-Zehnder to control the filtering function of the ring resonator. An all-pass filter within the ring resonator design is utilized to determine the optical path length difference in the Mach-Zehnder′s lower arm by modifying the effective refractive index through heating. This alteration in phase between the arms after combination allows for the observation of how changes in the lower arm phase affect the resonance frequency produced by the upper arm all-pass filter. The design optimizes the integration of the all-pass filter′s free spectral range (FSR) with the MZI’s FSR to facilitate switching between filtering and signal extraction functions.
The second part of this study validates the operational principles and transmission spectra of the ring resonator and Mach-Zehnder structures using MATLAB. Initial discussions cover the resonance conditions of the ring resonators and the distinctions between two types of ring resonators. The coupling states and the proportion of resonant optical power are analyzed. Importantly, parameters such as the power loss ratio 〖K_p〗^2 after light completes a cycle within the ring from the straight waveguide, and the power coupling ratio 〖K_e〗^2from the straight to the ring waveguide, along with Free Spectral Range (FSR), Full Width at Half Maximum (FWHM), Finesse, and Quality Factor, are thoroughly investigated.
Simulations using RSoft FemSIM confirm the effective and group refractive indices under various material and structural parameters, and the stability of the transverse electric (TE) mode. These parameters are converted into a single component format and exported as a Process Design Kit (PDK) for integration into OptSIM simulations. This approach streamlines photonics circuit modeling and verification, reducing the simulation time required. Thermal-Optic modulation aspects are explored using RSoft to determine the thermal impact on waveguide refractive indices. The simulation results are converted to PDK format for integration into OptSIM to observe phase changes under different temperature conditions and arm lengths of the Mach-Zehnder structure, confirming the phase shifts through changes in light intensity.
In the third part, five structural configurations are explored to analyze the passive and actively modulated characteristics of single Mach-Zehnder structures with equal and unequal arm lengths, and ring-coupled Mach-Zehnder configurations. The design of two types of thermal switches is simulated to confirm the relationships between heater placements, waveguide heights, and refractive indices across different materials. Using varying arm lengths, the activation and deactivation of resonance peaks in the all-pass filter are simulated to verify the thermal modulation effectiveness of the Mach-Zehnder′s lower arm, focusing on optical communication wavelengths between 1540 nm and 1560 nm. The switch performance is demonstrated, and the photomask layout and process compatibility are optimized by reducing the structural area and analyzing different bending radii in waveguides through FullWAVE FDTD simulations.
The fourth part details the sample fabrication process and measurement setup, including the equipment used and the methods for fitting the data. Passive and active measurements of ring-coupled equal and unequal arm length Mach-Zehnder structures are performed, followed by an analysis of the thermal switch structures based on sample measurements.
Finally, the fifth chapter evaluates the passive and modulated data from the study to confirm the modulation effects and discusses optimization improvements and tuning for optimal performance. |
