脉冲厄米高斯光束的载波相位分析*

采用复q参量法对脉冲厄米高斯光束在自由空间中的传输进行了分析.在振幅0阶和位相一阶近似条件下,得到其传播过程中载波位相近似公式.运用数值方法和近似公式进行对比研究,发现在脉宽大于5 fs或在远场情况下,两者符合较好.采用近似办法,分别研究了厄米函数阶次、束宽与位置对载波相位的影响.研究表明,在光轴上远场,载波相位趋近于－m+n+1π/2,其变化快慢与厄米函数阶次m+n+1成正比|束腰宽度越大,则载波相位变化越慢|另外,离光轴距离越远,其导致的载波相位越大,且最大位置都出现在z=ZRω0/3处.

Carrier Envelope Phase of Few Cycles Pulsed Hermite Gaussian Beam

The complex q parameter method is used to analyse the propagation of t the few cycles pulsed Hermite Gaussian beam in the free space within the paraxial condition,and an approxiatie formula for the carrier envelope phase (CEP) is deduced when the zero-order approximation in the amplitude and the first-order approximation in the phase are used.The validity of the approximation formula is verified by the numerical simulation methods,which shows that they fit well with each other if only the pulse duration is more than 5 femtosecond or the propagation distance is long enough.The order number of Hermite function,the beam waist and the position away from the axis play important roles in the CEP of the few cycles pulsed Hermite Gaussian beam,the conclusion as follows: the CEP trends to －m+n+1π/2 in the far field and its variety is inverse proportion with the beam waist on the axis.The distance away the axis is farer,the induced CEP is bigger and the position occurred at the point z=ZRω0/3.