CAJ | 학술논문

通过采用预估校正的时域有限差分法求解麦克斯韦-布洛赫方程,我们研究了飞秒激光脉冲在三能级有机分子(4, 4'-二甲氨基二苯乙烯分子)介质中传播时脉冲的频谱演化情况. 在单光子共振情况下,即入射脉冲频率等于1、2能级之间的共振频率,对大面积入射脉冲,由于强的二次激发的作用,电场频谱中出现了在ω32附近振荡的频率成分,ω32是2、3能级之间的共振频率,说明对大面积入射脉冲二能级模型已经失效,需要采用多能级模型来描述分子介质. 在双光子共振情况下,即入射脉冲频率等于1、3能级之间的共振频率的一半,由于介质中放大的自发辐射和四波混频的作用,部分入射脉冲能量转化为高频和低频电场成分的能量,分子介质表现出了很强的光功率限幅特性.
통과채용예고교정적시역유한차분법구해맥극사위-포락혁방정,아문연구료비초격광맥충재삼능급유궤분자(4, 4'-이갑안기이분을희분자)개질중전파시맥충적빈보연화정황. 재단광자공진정황하,즉입사맥충빈솔등우1、2능급지간적공진빈솔,대대면적입사맥충,유우강적이차격발적작용,전장빈보중출현료재ω32부근진탕적빈솔성분,ω32시2、3능급지간적공진빈솔,설명대대면적입사맥충이능급모형이경실효,수요채용다능급모형래묘술분자개질. 재쌍광자공진정황하,즉입사맥충빈솔등우1、3능급지간적공진빈솔적일반,유우개질중방대적자발복사화사파혼빈적작용,부분입사맥충능량전화위고빈화저빈전장성분적능량,분자개질표현출료흔강적광공솔한폭특성.
The spectrum evolution of the femtosecond laser pulse in a three-level organic molecular medium (4, 4'-bis(dimethylamino) stilbene) is studied theoretically by solving the Maxwell-Bloch equations using an iterative predictor-corrector finite-difference time-domain method. In the single-photon resonance case, for large area input pulses, the spectral components oscillating around ω32 appears in the spectrum due to the strong secondary excitation making the two-level model invalidity and the multi-level model should be used to describe this molecule. In the two-photon resonance case, part of the input pulse energy is transformed into higher and lower frequency components through amplified spontaneous emission and four-wave mixing, and the medium shows strong optical power limiting effect.