類雜訊脈衝之全光纖式高功率寬頻超連續光源

Abstract

在本論文中，我們成功利用類雜訊脈衝開發出一台全光纖式的高功率寬頻之超連續光源。為獲得此寬頻超連續光，需要一台高功率的類雜訊脈衝雷射來注入一段短非線性光纖。兩階段的光纖放大器被利用來大幅度地放大低功率鎖模光纖雷射所產生的類雜訊脈衝。該光纖放大器可對此小訊號達成30 dB的淨增益，並輸出達到13.2瓦的平均功率。該放大訊號再被送入非線性光纖來誘發強烈的非線性現象，並產生超連續光譜。在超連續光譜中，光譜功率密度在每奈米超過−10 dBm下的光譜可涵蓋990奈米到2280奈米。如此寬的光譜可滿足許多於不同波段需求的應用，亦橫跨摻鐿、摻鉺、摻铥的光纖雷射波段。此被開發的寬頻光源有著許多優點，例如：高空間同調性、自啟動、免保養、高光譜功率密度。此外，該光源可應用於光度量學、光感測、光學顯微鏡、生物醫學、光通訊之等領域。

An all-fiber, high-power broadband supercontinuum source was demonstrated using noise-like pulses pumping a short highly nonlinear fiber. To obtain this broadband supercontinuum, high-power noise-like pulses were launched into the highly nonlinear fiber. A passively mode-locked fiber laser with low-power noise-like pulses was significantly amplified using a two-stage fiber amplifier. The amplified noise-like pulse train with a 30-dB net gain in the cascaded amplifier, whose average output power reached 13.2 W, was sent into the highly nonlinear fiber to induce strong nonlinearities. A supercontinuum spectrum ranging from 990 nm to 2280 nm with a power spectral density of above −10 dBm/nm was generated. The spectrum obtained with such a power spectral density for noise-like pulses satisfies the requirements for applications within certain wavelengths, which also covers wavelength bands of all popular traditional fiber laser sources such as ytterbium-, erbium-, and thulium-doped fiber lasers. The developed broadband source has many advantages such as high spatial coherence, self-starting property, maintained-free, and high spectral power density. Such an all-fiber, high-power supercontinuum source has many useful applications in, for example, optical metrology, optical sensing, optical microscopy, biomedicine, and optical communication.