DSpace collection: 博碩士論文

古典吉他Tornavoz音管與側板音孔之聲學研究;Acoustic Study of Tornavoz Tubes and Side Sound Holes in Classical Guitars

title: 古典吉他Tornavoz音管與側板音孔之聲學研究;Acoustic Study of Tornavoz Tubes and Side Sound Holes in Classical Guitars abstract: 古典吉他當弦音與音孔空氣振動頻率接近或相同時，會導致兩峰值重疊，因此產生強耦合並形成狼音。本研究旨在探討此古典吉他弦音與音箱結構之間的共振耦合現象。並以模擬與實驗的方式提出避免產生狼音的方法。首先使用3D printer製作Tornavoz(音孔延伸管)安裝至古典吉他上。並使用撥弦裝置與雷射測距儀，來量測吉他的在撥動第四弦空弦時的振動頻譜。觀察Tornavoz音管長度對Body mode的頻率響應產生的變化。結果顯示，Body mode會隨著Tornavoz音管長度增加而下降，但卻不會影響其他的弦音，因此Tornavoz音管非常適合用來改善狼音。接著，將不同長度的Tornavoz音管(0-0.07m)作為變因，模擬並分析對共振頻率的調控效果，根據Helmholtz resonance的公式進行曲線擬合。由於文獻中沒有提到吉他音箱的L_eff，因此我們利用曲線擬合的結果可以得到Helmholtz 共振腔公式中，等效長度L_eff為音箱高度與Tornavoz音管長度之和。最後，將使用COMSOL Multiphysics 軟體進行模擬，觀察在吉他模型多挖一個側板音孔對頻率響應產生的變化。結果顯示，頻率方面有無側板音孔對頻率響應的影響很大，但側板音孔的形狀卻對頻率響應的影響很小。聲場的均勻性方面，傳統音孔在音量投射與正前方聲能集中表現優異，但在聲場均勻性與側向聲能上略顯不足。側板音孔可以使聲壓場在空間中均勻擴散，提供較為溫潤的聆聽感受。但側板方形音孔在高頻時，聲波可能偏移至側向、導致背板輻射不足，因此為三者中吉他後方聲能最低的。側板圓形音孔則在三頻段中皆展現穩定且均衡的輻射特性，為兼顧音量、均勻度與方向性之折衷設計。;When the string resonance of a classical guitar coincides or closely aligns with the air resonance frequency of the soundhole, two resonance peaks may overlap, resulting in strong coupling and the occurrence of a wolf tone. This study aims to investigate the resonance coupling phenomenon between string vibrations and the guitar body structure, and to propose methods—through both simulation and experiment—to mitigate wolf tones. First, a Tornavoz (a soundhole extension tube) was fabricated using a 3D printer and installed on a classical guitar. A plucking device and laser rangefinder were used to measure the vibration spectrum when the open 4th string was excited. The effect of Tornavoz soundtube length on the Body mode frequency response was analyzed. Results show that the Body mode frequency decreases with increasing Tornavoz soundtube length, while other string modes remain unaffected, indicating that Tornavoz soundtube is a suitable solution for wolf tone suppression. Subsequently,simulations were conducted with varying Tornavoz soundtube lengths (0–0.07 m) to analyze the tuning effect on the resonance frequency. A curve-fitting process based on the Helmholtz resonance equation was applied. The fitting results indicate that the effective length L_eff in the Helmholtz formula can be expressed as the sum of the guitar body′s internal height and the Tornavoz soundtube length. In addition, we used COMSOL Multiphysics simulations to investigate how adding an auxiliary side soundhole affects the guitar’s frequency response. The results reveal that while the presence of a side hole significantly alters the frequency response, the shape of the hole has minimal impact. In terms of sound field uniformity, the traditional soundhole design excels in front-facing projection and energy concentration but shows weaker lateral energy distribution. The side soundhole design enables more spatially uniform dispersion of acoustic pressure, offering a warmer and more balanced listening experience. However, the square side soundhole shows signs of lateral energy deviation at high frequencies, leading to weaker radiation from the back plate, making it the least effective among the three in terms of rear acoustic power. In contrast, the circular side soundhole demonstrates stable and balanced radiation characteristics across all frequency bands, making it a well-rounded design in terms of sound pressure level, uniformity, and directional response.

單中心多尺度超大廣角遠距偵查光學系統

title: 單中心多尺度超大廣角遠距偵查光學系統 abstract: 本論文提出一種用於遠距偵查應用之單中心多尺度超大廣角光學系統之完整設計、分析與驗證方法。該系統以單中心（single-center）光學架構為核心，結合多尺度子鏡頭拼接策略，在有限系統體積下同時實現超大視角覆蓋與遠距目標解析能力。於本研究所設計之系統中，可達成水平視角 110 度、垂直視角 72 度之廣角成像範圍，並透過多子鏡頭整合拼接，實現總畫素數約 49.8 億畫素之高解析成像效能，適用於長距離目標之偵測（detection）、辨識（recognition）與鑑別（identification）等遠距偵查任務。在光學設計階段，本研究使用 CODE V 進行單中心光學系統之成像設計與最佳化。藉由單中心光學系統中各光學面共用球心之幾何特性，使系統於理論上具備良好的像差對稱性與離軸延展能力，從而降低超大視角與遠距高解析需求並存時之設計複雜度，並有利於多尺度子鏡頭之系統化配置。在系統效能評估方面，本研究以 Johnson Criteria 作為任務導向之核心設計依據，將遠距偵查需求直接轉化為系統解析度、視角配置與像素取樣密度等設計指標。此外，針對所提出之單中心多尺度光學系統，進行完整之光學公差分析，並考量切向與徑向方向光線對成像品質影響機制之差異，分別評估加工公差與組裝公差對系統解析效能之影響。透過蒙地卡羅分析與補償策略設定，在累積機率 97.7% 的條件下評估系統成像品質，並以調制傳遞函數（MTF）作為量化指標，驗證系統於合理公差範圍內仍可滿足遠距偵查任務之解析需求。此外，為驗證系統於實際應用情境下之整體表現，本研究進一步使用 LightTools 進行影像級光線追跡模擬，以模擬真實遠距偵查條件。透過此影像模擬流程，可同時評估多尺度子鏡頭於拼接前後之影像連續性，以及雜散光與鬼影效應對整體影像品質之影響，從系統層級驗證所提出架構於遠距偵查應用上的可行性。 ;This dissertation proposes a complete design, analysis, and validation methodology for a monocentric ultra-high-pixel wide-angle high-resolution optical system for long-range reconnaissance applications. The proposed system is based on a monocentric (single-center) optical architecture and integrates a multi–sub-lens image stitching strategy. Under an ultra-wide field-of-view condition of 110° horizontally and 72° vertically, the system simultaneously achieves a total resolution of approximately 4.98 billion pixels (5 billion pixels), and is suitable for long-range reconnaissance tasks such as target detection, recognition, and identification. In the optical design stage, CODE V is employed to perform image-forming optical design and optimization of the lens system. By utilizing the geometric characteristic of a monocentric optical system, in which all optical surfaces share a common center of curvature, the system theoretically exhibits good aberration symmetry and off-axis extension capability. This characteristic effectively reduces the design complexity associated with simultaneously achieving large field of view and high resolution. For system performance evaluation, Johnson Criteria is adopted as the mission-oriented core design basis, enabling long-range reconnaissance requirements to be directly translated into design parameters including system resolution, field-of-view configuration, and pixel sampling density. In addition, a comprehensive optical tolerance analysis is conducted for the proposed monocentric multi–sub-lens optical system. The differences in image degradation mechanisms between tangential and sagittal ray directions are explicitly considered, and the impacts of manufacturing tolerances and assembly tolerances on system resolution performance are evaluated separately. Monte Carlo analysis combined with compensation strategies is performed to assess system image quality under a cumulative probability of 97.7%, and the modulation transfer function (MTF) is used as a quantitative metric to verify that the system can maintain resolution performance that satisfies reconnaissance mission requirements within reasonable tolerance ranges. Furthermore, to validate the overall system performance under practical application scenarios, LightTools is employed to conduct image-level ray-tracing simulations that emulate realistic long-range reconnaissance conditions. Through this image-based simulation process, both the image continuity before and after multi–sub-lens stitching and the effects of stray light and ghost reflections on image quality are evaluated.

氮化矽優化之薄膜鈮酸鋰波導絕熱耦合偏振分光器之研究;Silicon nitride-optimized thin-film lithium niobate waveguide polarization mode splitter based on optical adiabatic passage mechanism

title: 氮化矽優化之薄膜鈮酸鋰波導絕熱耦合偏振分光器之研究;Silicon nitride-optimized thin-film lithium niobate waveguide polarization mode splitter based on optical adiabatic passage mechanism abstract: 本研究致力於研製出薄膜鈮酸鋰（Lithium Niobate-on-Insulator，LNOI）為基礎之波導元件，並且利用其材料特性達到低損耗、高折射率對比使得元件長度能進一步變得更加緊湊。透過 LNOI 與異質材料之結合，可有效放大結構設計上的自由度，進一步提升元件整體效能。模擬上採用x-cut LNOI進行設計，利用RSoft光學軟體中的光束傳播方法(Beam propagation method，BPM)進行分析，首先會模擬出雷射光源進入至脊型波導(Rib Waveguide)的傳輸情形，接著進一步模擬和分析出絕熱耦合器(Adiabatic Coupler，AC)結構，以實現偏振態的有效分離。再進一步透過氮化矽(Silicon Nitride)之異質材料整合，優化出的被動元件將實現高寬頻（high broadband）的偏振模態分光器(Polarizing Mode Splitter，PMS)。實驗上使用半導體相關設備進行黃光、微影、薄膜鍍膜、乾式蝕刻等技術進行實驗，透過跨區域型的製作來整合達成目標。其主要蝕刻波導使用的機器為感應耦合電漿反應離子蝕刻(Inductively Coupled Plasma-Reactive ion etching，ICP RIE)進行波導蝕刻，成功做出脊型波導並且把蝕刻過後的剩餘殘留物(Redepositions)進行完整移除，確保波導側壁與傳輸損耗的有效降低。在未來，結合本實驗室所發展之鈮酸鋰材料極化反轉（poling）技術，可進一步引入非線性光學現象，使該元件不僅具備偏振操控能力，亦能實現波長轉換、糾纏光子產生與量子態操控等功能，拓展至量子光學與量子量測相關應用。透過精確設計的波導結構與極化區域分佈，在同一晶片上整合偏振分離、非線性轉換，提升量子系統的整體穩定度。藉由優化異質材料波導幾何，未來可針對更寬操作頻譜與更高製程容忍度進行設計，提升元件在實際製程與系統應用中的可靠度。此發展將有助於建構出量子積體光路（Quantum Photonic Integrated Circuits，QPICs）平台。;This thesis focuses on the development of waveguide devices based on lithium niobate on insulator (LNOI). By utilizing the material properties of LNOI, including low optical loss and high refractive index contrast, the device length can be further reduced, enabling more compact integrated structures. In addition, the combination of LNOI with heterogeneous materials provides greater flexibility in structural design and improves overall device performance. In the simulation stage, x-cut LNOI is used as the substrate material. The optical characteristics are analyzed using the beam propagation method (BPM) implemented in the RSoft optical simulation software. First, the propagation behavior of a laser source in a rib waveguide is simulated. An adiabatic coupler (AC) structure is then designed and analyzed to achieve effective separation of different polarization states. Furthermore, by integrating silicon nitride (SiN) as a heterogeneous material, the passive device is optimized to realize a high-broadband polarization mode splitter (PMS). For the fabrication process, standard semiconductor microfabrication techniques, including photolithography, thin-film deposition, and dry etching, are employed. A cross-region integration approach is adopted to complete the device fabrication. The waveguides are mainly etched using inductively coupled plasma reactive ion etching (ICP-RIE), successfully forming rib waveguide structures. Redeposition residues generated during the etching process are effectively removed, ensuring improved sidewall quality and reduced propagation loss. In future work, by combining the electric-field poling technique for lithium niobate developed in our laboratory, nonlinear optical effects can be introduced into the proposed devices. This allows the devices to support wavelength conversion, entangled photon generation, and quantum state manipulation, extending their applications to quantum optics and quantum measurement. Through precise design of waveguide structures and poling region distributions, polarization separation and nonlinear optical functions can be integrated on a single chip, improving system stability. Further optimization of heterogeneous waveguide geometries is expected to enable broader operating bandwidths and higher fabrication tolerance, contributing to the development of quantum photonic integrated circuits (QPICs).

基於介面能階工程與光閘效應之鈣鈦礦光敏偵測器與電晶體研究;Research on Perovskite Photodetectors and Phototransistors Based on Interfacial Energy Level Engineering and Photogating Effect

title: 基於介面能階工程與光閘效應之鈣鈦礦光敏偵測器與電晶體研究;Research on Perovskite Photodetectors and Phototransistors Based on Interfacial Energy Level Engineering and Photogating Effect abstract: 本研究主要在開發結合鈣鈦礦（MAPbI3）與金屬氧化物之光偵測元件，研究架構系統性地涵蓋橫向 / 垂直光敏二極體及橫向光敏電晶體，並針對不同幾何結構之物理機制進行探討。在橫向光敏二極體方面，本研究對比了不同功函數之電子傳輸層對元件性能的影響。實驗結果顯示，導入功函數為 3.9 eV 之 ZnO NPs 具備顯著優勢，能有效降低暗電流並提升光電流，在波長 472 nm (1 mW/cm2) 照射下，其外部量子效率 (EQE) 達 70.7%，響應度為 0.269 A/W。相較之下，功函數為 4.3 eV 之元件受限於能階匹配不佳與較高密度的介面缺陷，其 EQE 僅為 7.5%，響應度為 0.028 A/W，證實了能階調控對優化橫向架構性能的重要性。在垂直光敏二極體方面，利用其奈米級短通道之幾何優勢，有效縮短載子漂移路徑。研究結果顯示，透過電極功函數差異與電荷傳輸層能階梯度所建立的內建電場，使元件展現優異的自供電特性。在零偏壓操作下，元件仍能維持穩定的光電流輸出與脈衝光響應，達到 29.3 % 的 EQE。在橫向光敏電晶體架構中，本研究以原子層沉積（ALD）技術生長之氧化鋅（ZnO）作為 n 型半導體通道層，並於上方依序旋塗在橫向二極體中優化後之鈣鈦礦吸光層。透過引入 ALD-Al2O3 作為介面層，成功誘導出光閘效應（Photogating effect），並藉由場效耦合作用顯著提升元件的光學增益。最終，結合鋁摻雜氧化鋅（AZO）傳輸層，成功將 EQE 提升至 1070%，響應度達 4.07 A/W，展現了卓越的弱光偵測靈敏度。 ;This research focuses on the development of hybrid photodetecting devices combining perovskite (MAPbI3) and metal oxides. The study systematically investigates three distinct architectures—lateral photodiodes, vertical photodiodes, and lateral phototransistors—and analyzes the physical mechanisms underlying each configuration. Regarding lateral photodiodes, the impact of electron transport layers with different work functions on device performance was compared. Experimental results demonstrate that incorporating ZnO NPs with a 3.9 eV work function provides significant advantages, effectively reducing dark current and enhancing photocurrent. Under illumination at a wavelength of 472 nm(1 mW/cm2), the device achieved an External Quantum Efficiency (EQE) of 70.7% and a responsivity of 0.269 A/W. In contrast, the 4.3 eV ZnO device exhibited inferior performance due to poor energy alignment and high interface defect density, yielding an EQE of only 7.5% and a responsivity of 0.028 A/W, highlighting the importance of energy level engineering for optimizing lateral architectures. In the case of vertical photodiodes, the nanometer-scale short-channel geometry was utilized to effectively minimize carrier drift paths. The results indicate that the built-in electric field, established through electrode work function differences and energy level gradients, enables excellent self-powered characteristics. Under zero-bias conditions, the device maintains stable photocurrent output and pulse photoresponse, achieving an EQE of 29.3%. For the lateral phototransistor architecture, an atomic layer deposition (ALD) grown zinc oxide (ZnO) film serves as the n-type semiconductor channel, with the optimized perovskite light-absorbing layer from the lateral photodiode section subsequently spin-coated on top. By introducing ALD-Al2O3 as an interfacial layer, a robust photogating effect was successfully induced, significantly enhancing optical gain through field-effect coupling. Finally, combining aluminum-doped zinc oxide (AZO) transport layer, the EQE was boosted to 1070% with a responsivity of 4.07 A/W, demonstrating exceptional sensitivity for weak-light detection.