高峰值光场的定点产生

Fixed-point generation of large high peak optical field

用有限差分方法联立求解Maxwell-Bloch方程时,发现2π光脉冲通过1维共振介质时的两个现象:当共振介质的偶极矩较大或共振粒子数密度较大时,2π脉冲波形会发生分裂,不再以孤子形式传播;峰面积符号相同、脉宽不同的两个2π脉冲传播时,脉宽小的脉冲将赶上脉宽大的脉冲,赶超过程中光电场大小的变化不明显,而峰面积符号相反、脉宽不同的脉冲在赶超过程中会引起光场的叠加而形成光电场峰值高、脉宽小的脉冲,因而可以通过控制两脉冲的相对脉宽或相对距离,在介质的指定位置产生高峰值的光场。

The propagation regularity of the laser in the 1D resonance media was studied by solving the Maxwell-Bloch equations with definite difference method. It was found that the 2π pulse would not propagate as a soliton but split if the dipole moment or the particles concentration of the resonance media was over a certain value. When two 2π pulses of different pulse widthes propagated through the resonance media, the shorter-duration pulse would catch up with the longer one. If the peak area signs of the two pulses were the same, the optical field indensity would not change obviously, it would add up and a powerful pulse with larger peak area but shorter duration would be generated. Therefore a powerful field could be generated on a fix position by adjusting the pulse width or time lapse of the two pulses properly.