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

Abstract

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。

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.