静电场对V型三能级介质中传播的超短脉冲频谱CEP相关性的影响

EFFECT OF STATIC ELECTRONIC FIELD ON CEP- DEPENDENT SPECTRUM OF ULTRASHORT PULSE PROPAGATIONG IN V- TYPE THREE- LEVEL MEDIUM

利用由预估校正（PC）-时域有限差分（FDTD）法得到的Maxwell—Bloch方程的数值解研究了静电场对在V型三能级介质中传播的飞秒超短激光脉冲频谱载波包络相位（CEP）相关性的影响．结果表明：未加入静电场时，CEP的变化对脉冲频谱中较低频率部分的强度有较明显的影响，而对高频部分的影响很微弱，频谱平坦性和连续性较差；加入静电场后，CEP对频谱强度尤其是较高频部分强度的影响变大，通过选择适当的静电场和CEP的值可以获得平坦性和连续性较好的超连续谱．另外，静电场的加入还使得到相同频谱分布所对应的CEP周期由π改变为2π．

This paper investigated effect of static electronic field on CEP - dependent spectrum of femtosecond laser pulse propagating in a V - type three - level atomic medium by using numerical solution, which is obtained by PC - FDTD method of the Maxwell - Bloch equation. It is shown that when the static eleStronic field is absent, variation of CEP has a considerable effect on strength of the lower - frequency components of the pulse spectrum, but only has a weaker effect on the high -frequency components, and spectral flatness and continuity are worse. When the static electronic field presents, effect of CEP on the spectral strength, especially on strength of the high - frequency components, increases. By choosing appropriate values of the static electronic field and CEP, a supercontinuum With better flatness and continuity can be obtained. In addition, the static field makes the CEP period corre- sponding to the same spectral distribution change from π to 2π.