高峰值摻鐿光纖飛秒雷射放大器之研究

Abstract

本文中介紹了如何建構高峰值雷射放大器系統。種子源為使用半導體可飽和吸收鏡的被動鎖模光纖雷射，輸出功率為27mW，重複率為30MHz，脈衝寬度為6ps。為了去避免光纖非線性效應，我們採用啁啾脈衝放大(Chirp Pulse Amplification, CPA)系統。此架構分為三部分，包含光纖展寬器(Fiber strectcher)、光纖放大器系統(Fiber amplifier systems)、壓縮器(Compressor)。光纖展寬器可使光源脈衝寬度變寬，去降低峰值伴隨的非線性效應。在光纖放大器系統中，我們期望以更低平均功率達到相同脈衝能量。因此，藉由加入聲光調變器去降低脈衝雷射的重複率。最終我們完成了三級摻鐿光纖雷射放大器。在1MHz重複率時有3W平均功率輸出，脈衝寬度為96.98ps。在光柵入射角為27度時且光柵間距為65公分時，通過繞射光柵壓縮器可將脈衝壓縮回679fs，此時可造成大於1MW的峯值功率。

In this thesis, we introduce how to construct high peak power laser amplifier systems. The seed source is a passively mode-locked fiber laser using semiconductor saturable absorber mirrors (SESAM). The average power is 27mW at a repetition rate of 30MHz.The pulse width is 6ps. In order to avoid fiber nonlinear effect, we adopt chirp pulse amplification system. Three major components are included: Fiber strectcher, Fiber amplifier systems and Compressor, respectively. The pulse width of light source can be broadened by the fiber stretcher, reducing the peak power accompanied with nonlinear effect. As for fiber amplifier systems, we reduce the repetition rate of pulse laser by adding acoustic optical modulator (AOM) in an effort to use lower average power to achieve the same pulse energy. In the end, we finish three-stage Yb-doped fiber laser amplifier. The average power is 3W at a repetition rate of 1MHz.The pulse width is 96.98ps. These pulses can be further recompressed down to 679 fs after passing through a diffraction grating compressor when the incident angle is 27 degree and gratings separation is 65cm. The result makes a peak power over 1MW.