利用耦合波理论,分析了一种作为KrF准分子激光MOPA系统的振荡源-亚皮秒超短脉冲分布反馈染料激光器(DFDL)的输出模式,指出实际的分布反馈染料激光器工作在单纵模状态是周期性增益调制的必然结果.数值模拟结果表明,DFDL输出光谱出现多条谱线的精细结构或调制现象,这是由多个顺序相干脉冲产生的.可以利用这种光谱调制现象来控制激光器的泵浦强度,获得稳定的单脉冲.光谱测量结果表明,在2倍泵浦阈值左右DFDL能够获得稳定的单模单脉冲输出.

The output modes of sub-picosecond ultrashort pulse distributed feedback dye laser which is used as an oscillator for a high brightness KrF laser system were analyzed with coupling wave theory. The analysis shows that for a practical distributed feedback dye laser, single longitudinal mode oscillation is always obtained because of periodical gain modulation. A method based on spectrum modulation measurement to obtain a stable single pulse operation of DFDL was provided as well as numerical simulation.The measured spectrum shows that for the sub-picosecond DFDL used in the laser system, a stable single pulse, single longitudinal mode output is obtained under two times above pumping threshold.