短脈衝摻鐿光纖雷射及光子晶體光纖產生超連續光譜之研究

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(1)國立台灣師範大學光電科技研究所碩士論文. Institute of Electro-Optical Science and Technology National Taiwan Normal University. 短脈衝摻鐿光纖雷射及光子晶體光纖產生超連續光譜之研究 A study on short-pulse Yb-doped fiber laser and the supercontinuum generation in photonic crystal fiber 指導教授：鄭超仁博士共同指導教授：林奎輝博士研究生：張耕瑋中華民國. 一○一. 年一月.

(2) 摘要在本篇論文中，我們研製出了一種具有極寬波長範圍的高功率超連續光譜光纖光源，並將其應用在材料的光學特性量測。我們研製了可調式環形腔摻鐿光纖雷射，其操作模式可在連續波、 Q 開關鎖模、基頻鎖模和諧波鎖模之間切換。連續波輸出時之雷射波長可從 1065 nm 調整至 1082 nm，基頻鎖模時之脈衝寬度則可從約 200 ps 調整至約 6 ns。我們成功地熔接了傳統單模光纖與光子晶體光纖，使得雷射光從單模光纖至光子晶體光纖的耦合效率最高可以達到 77%。我們將摻鐿光纖雷射產生的脈衝經過摻鐿光纖放大器進行能量放大，再耦合進入非線性光子晶體光纖，成功地得到帶寬超過 1100 nm 的光纖超連續光譜。我們量測了光纖超連續光譜的穩定度、同調長度和脈衝寬度，並且使用光纖超連續光譜來量測石墨烯及葉綠素的穿透特性。關鍵詞：超連續光譜、摻鐿光纖雷射、短脈衝、光纖熔接、光子晶體光纖。. I.

(3) Abstract In. this. study, we have. demonstrated a. high-power fiber. supercontinuum (SC) source with wide spectral range, and use it to measure the optical properties of materials. A tunable mode-locked ytterbium-doped fiber ring laser is built. The operation state could be switched among continuous wave (CW), Q-switched mode-locking, fundamental mode-locking and harmonic mode-locking. For CW operation, the laser wavelength could be tuned from 1065 nm to 1082 nm. For fundamental mode-locking, the pulse duration could be tuned from 200 ps to 6 ns. We have fusion spliced the photonic crystal fiber (PCF) with the traditional single-mode fiber, and the highest coupling efficiency is about 77%. A ytterbium-doped fiber amplifier (YDFA) is used to amplify the pulses from the tunable mode-locked ytterbium-doped fiber laser. By injecting the amplified pulses into the nonlinear PCF, broad bandwidth SC generation of over 1100 nm have been achieved. We have measured the stability, coherence length and pulse duration of supercontinuum, and use the SC source to measure the transmission spectra of graphene and chlorophyll. Key words：supercontinuum 、ytterbium-doped fiber ring laser、 short-pulse、fiber fusion splice、photonic crystal fiber. II.

(4) 目錄摘要 ........................................................................................................... I Abstract ..................................................................................................... II 目錄 ......................................................................................................... III 圖目錄 ..................................................................................................... VI 表目錄 ..................................................................................................... IX 第一章緒論 ............................................................................................ 1 1.1 研究動機及目標 ............................................................................ 1 1.2 文獻分析 ......................................................................................... 2 1.2.1 短脈衝光纖雷射 ...................................................................... 2 1.2.2 光子晶體熔接 .......................................................................... 3 1.2.3 超連續光譜產生 ...................................................................... 3 1.3 論文架構 ........................................................................................ 5 第二章短脈衝摻鐿光纖雷射 ................................................................. 6 2.1 摻鐿光纖雷射介紹 ........................................................................ 6 2.1.1 雷射 .......................................................................................... 6 2.1.2 光纖雷射 .................................................................................. 8. III.

(5) 2.1.3 摻鐿光纖雷射 .......................................................................... 9 2.2 短脈衝產生機制 .......................................................................... 10 2.2.1 飽和吸收體 ............................................................................ 10 2.2.2 非線性偏振旋轉 .................................................................... 11 2.3 短脈衝摻鐿光纖雷射實驗架設 ................................................... 12 2.4 實驗結果及分析 .......................................................................... 14 2.4.1 操作模式切換 ........................................................................ 14 2.4.2 脈衝寬度量測 ........................................................................ 15 2.4.3 光譜量測 ................................................................................ 17 第三章光纖熔接技術........................................................................... 19 3.1 光纖熔接及光子晶體光纖介紹 ................................................... 19 3.2 光纖熔接機 .................................................................................. 22 3.3 實驗結果及分析 .......................................................................... 24 第四章光纖超連續光譜....................................................................... 26 4.1 超連續光譜介紹 .......................................................................... 26 4.2 超連續光譜產生機制 .................................................................. 27 4.3 光纖超連續光譜實驗架設........................................................... 29 IV.

(6) 4.3.1 光纖超連續光譜系統 ............................................................ 29 4.3.2 同調長度量測實驗 ................................................................ 30 4.4 光纖超連續光譜的應用............................................................... 31 4.4.1 石墨烯量測實驗 .................................................................... 31 4.4.2 葉綠素溶液量測實驗 ............................................................ 32 4.5 實驗結果及分析 ........................................................................... 33 4.5.1 光譜量測 ................................................................................ 33 4.5.2 脈衝寬度量測 ........................................................................ 35 4.5.3 同調長度量測 ........................................................................ 36 4.5.4 石墨烯量測 ............................................................................ 37 4.5.5 葉綠素溶液量測 .................................................................... 38 第五章結論與未來工作....................................................................... 39 參考文獻 ................................................................................................ 41. V.

(7) 圖目錄圖 1.1 摻鐿光纖雷射：(a) 光譜及 (b) 雷射脈衝。 ...................... 2 圖 1.2 光子晶體光纖與一般光纖熔接結果： (a) 熔接前， (b) 熔接後；左側為光子晶體光纖。 ........................................................... 3 圖 1.3 超連續光譜實驗結果。 ........................................................... 4 圖 1.4 超連續光譜之光譜量測。…………………………………………………….4 圖 2.1 受激光放大的原理示意圖 (a)吸收，(b)自發發射，(c)受激發射。 ...................................................................................................... 6 圖 2.2 簡單的雷射結構 ....................................................................... 7 圖 2.3 摻鐿光纖的吸收和螢光光譜。 ............................................... 9 圖 2.4 飽和吸收體示意圖： (a) 快速吸收體， (b) 慢速吸收體；下方為脈衝。 ..................................................................................... 11 圖 2.5 短脈衝摻鐿光纖雷射 ............................................................. 12 圖 2.6 摻鐿光纖放大器的增益光譜 ................................................. 13 圖 2.7 脈衝量測架構圖 ..................................................................... 13 圖 2.8 不同操作模式之脈衝列量測： (a) 基頻鎖模， (b) 諧波鎖模， (c) Q 開關鎖模。 ..................................................................... 14 圖 2.9 脈衝寬度調整： (a) 203 ps、 (b) 575 ps、 (c) 1.93 ns、 (d) 3.16. VI.

(8) ns、 (e) 5.95 ns。 .............................................................................. 16 圖 2.10 脈衝分裂： (a) 2 個脈衝， (b) 3 個脈衝。 ...................... 17 圖 2.11 在連續波操作時的波長調變： (a) 中心波長 1065 nm，(b) 中心波長 1082 nm。 .......................................................................... 17 圖 2.12 不同操作模態之光譜量測： (a) 基頻鎖模， (b) 諧波鎖模， (c) Q 開關鎖模。 ............................................................................... 18 圖 3.1 SC-5.0-1040 的 SEM 截面圖。 ............................................. 21 圖 3.2 光纖熔接機 FSM-60S............................................................ 22 圖 3.3 FSM-60 之參數條件................................................................ 23 圖 3.4 熔接結果：(a) 熔接前，(b)熔接後。 .................................. 24 圖 4.1 超連續光譜與其他寬頻光源的光譜比較 ............................. 26 圖 4.2 超連續光譜的產生機制 ......................................................... 27 圖 4.3 全光纖之超連續光譜系統 ..................................................... 29 圖 4.4 同調長度量測實驗 ................................................................. 30 圖 4.5 石墨烯量測實驗 .................................................................... 32 圖 4.6 葉綠素光譜量測實驗 ............................................................. 32 圖 4.7 不同入射功率所產生之超連續光譜：(a) 100 mW、(b) 200 mW、 (c) 300mW、(d) 400mW、(e) 500mW、(f) 600mW。 .................... 33 圖 4.8 不同操作模式之脈衝入射至非線性光子晶體光纖所產生之. VII.

(9) 超連續光譜：(a) 連續波鎖模脈衝，(b) Q 開關鎖模脈衝。.......... 34 圖 4.9 超連續光譜之穩定度測試 ..................................................... 35 圖 4.10 脈衝波形量測：(a) 入射之鎖模脈衝，(b) 超連續光譜脈衝。 .......................................................................................................... 35 圖 4.11 超連續光譜的干涉條紋： (a) 連續波鎖模， (b) Q 開關鎖模。 ................................................................................................. 36 圖 4.12 連續波鎖模之超連續光譜同調長度： (a) 對比度量測結果， (b) 線性平移台之步進大小。 .......................................................... 36 圖 4.13 石墨烯的吸收光譜 ............................................................... 37 圖 4.14 葉綠素溶液的量測結果 ....................................................... 38. VIII.

(10) 表目錄表 3.1 Corning HI 1060 單模光纖規格 .............................................. 20 表 3.2 NKT Photonics SC-5.0-1040 光子晶體光纖規格 ................... 20 表 3.3 耦合效率量測結果 ................................................................. 25. IX.

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