漸寬型半導體雷射放大器中次皮秒

Abstract

在本碩士論文的工作中，我們架設了一套可即時監控超短脈衝的干涉式自相干儀。具有線性啾頻的高斯波形飛秒脈衝，其干涉式自相干軌跡可利用富利葉分析以解析解的形式加以描述。此自製的干涉式自相干儀是藉由轉換極限飛秒脈衝輸出的鈦藍寶石雷射進行校正。 利用此具干涉式自相干儀，我們研究了次皮秒脈衝在漸寬型半導體雷射光放大器中的注入放大行為。入射光脈衝寬度為90飛秒且為轉換極限，脈衝致寬和啾頻等行為在光放大後被觀察，我們發現當工作電流從596mA(I=0.98Ith)增加到662mA(I=1.1Ith)時，脈衝寬由480飛秒增加到530飛秒；啾頻的數量級為1024sec-2。我們也首度報導了次皮秒光脈衝在漸寬型半導體雷射光放大器中的群速度色散參數：約為250fs/nm，這和文獻中所報導單條型半導體雷射光放大器的這兩個參數，在數量級上是相同的。

In the work, we have constructed an interferometric autorrelator to monitor ultrafast optical pulses in real time. Using Fourier analysis, the interferometric autocorrelation trace of Gaussian-shaped femtosecond pulses with linear chirp were described analytically. The home-made interferometric autocorrelator was calibrated with a transform-limited femtosecond Ti-Sapphire laser. Using the interferometric autocorrelator, we have characterized subpicosecond pulses injection-amplified in a tapered semiconductor optical amplifiers (SOA's). The optical pulse before amplification is transform-limited. The pulse was Gaussian in shape and the width was about 90 fsec. The broader amplified subpicosecond pulses with chirping have been observed. We find the pulsewidth broadened from 480 fsec to 530 fsec as the bias cureent increased from 596mA (I=0.98Ith) to 662mA (I=1.1Ith). The order of magnitude of the chirp parameter was about 1024sec-2. We also reported for the first time that the chirp and GVD parameter (~250fs/nm) of the tapered SOA is of the same order magnitude as that of single stripe devices.