【摘要】 给出了一种精确描述超短、紧聚焦激光脉冲的新方法 ,其思路是根据两个无量纲小量ε =1 (ω0 t0 )和s =1 (k0 w0 ) (其中ω0 =ck0 为中心振荡频率 ,t0 为脉冲延迟时间 ,w0 为激光束腰半径 )进行展开来计算脉冲的高阶修正场 .在激光束近轴近似表达式的基础上 ,给出了高斯脉冲一阶修正场的解析表达式 ,并研究发现其振幅和相位相对于零阶修正场 (即长脉冲近似 )的修正量都在ε的量级甚至更小 .另外对电子在超短高斯脉冲一阶修正场中的动力学特性研究发现 :对于ω0 t0 >2 0的情况 ,零阶修正场可以正确地描述电子被光场加速的特性 ;当ω0 t0 <2 0时 ,则需要采用高阶修正场 .更多还原

【Abstract】 High-order correction to the fields of ultrashort, tightly-focused laser pulse s expressed in power series of ε=1/(ω 0t 0) and s=1/(k 0w 0)(ω 0= ck 0 the central oscillatory frequency, t 0 the pulse duration, w 0 the beam waist radius), are derived. Based on paraxial approximation, the first -order correction terms to the Gaussian pulses are explicitly given. Their corr ections of amplitude and phase, are found to be related to the variable of ε . Applying them to the study of the electron dynamics in the intense laser pul se field, we found that as long as ω 0t 0>20, the zeroth-order approxima tion (long pulse approximation) is adequate for describing the interaction. For ω 0t 0<20, higher-order corrections have to be taken into account.更多还原