Ultrafast spectroscopy by using laser diode

研究项目的目的分为两个项目。一种是找到一种简单的方法，通过使用商业上可用的传统半导体激光器来获得超短激光脉冲。二是利用半导体光学器件发展超快光谱新技术。主要研究结果如下：1.可以在半导体激光器的输出面上涂覆良好的减反射膜。1.利用镀膜减反射激光二极管在外腔获得锁模振荡。脉冲宽度为10ps，脉冲能量为10pJ，重复频率为100 MHz。1.利用调Q激光倍频光激发的染料池放大器，放大了上述皮秒半导体激光器(脉冲宽度30ps，脉冲能量10pJ)的输出。获得了约106的放大倍数，脉冲宽度为40ps，脉冲能量为40uJ，重复频率为1 Hz。1.证明了多模半导体激光器和超辐射二极管可以作为非相干光光子回波实验的激发光源。1.首次使用非激光光源--普通型发光二极管，成功地观测到了积累的光子回波。非激光光源的使用将把光子回波实验扩展到目前无法获得激光的波长区域。

The purpose of the research project is divided into two items. One is to find a simple method to get ultrashort laser pulses by using commercially available conventional diode lasers. And the other is to develop a new technique of ultrafast spectroscopy by using semiconductor optical devices. Summary of the results are as follows: 1. We could apply good anti-reflection coatings to the output facets of laser diodes. 1. Mode-locking oscillation was obtained in an external cavity by using the anti-reflection coated laser diode. The pulse width, pulse energy and the repetition rate were 10 ps, 10 pj and 100 MHz, respectively. 1. The output of the above mentioned picosecond diode laser (pulse width 30 ps, pulse energy 10 pJ) was amplified by using a dye cell amplifier excited by the second harmonic light of a Q-switched YAG laser. The amplification of about 10^6 was obtained, and the pulse width, pulse energy and repetition rate of the output were 40 ps, 40 uJ and 1 Hz, respectively. 1. We showed that multi-mode diode lasers and superluminescent diodes can be used as the excitation light source for incoherent light photon echo experiments. 1. We succeeded in observing accumulated photon echoes for the first time by using a non-laser light source, a normal type light emitting diode. The use of non-laser light source will extend the photon echo experiment into the wavelengthregions where lasers are not presently available.