飞秒激光脉冲经小孔衍射后的近场光强节点

应用数值求解格林函数的方法，计算模拟了飞秒脉冲通过亚波长小孔的衍射光场. 首先将具有高斯时间轮廓的飞秒脉冲展开成一系列简谐光波的叠加，对每一个频率的简谐光波进行数值计算，得到该频率的衍射光场的空间分布, 然后对所有频率的衍射光场进行反傅里叶变换得到光场随时间的变化.分析发现,飞秒脉冲通过小孔后沿界面向小孔两边传播，并且在该传播过程中, 衍射光场会在介质的分界面上和在接近界面的区域中形成光强的节点.

Nodes of the near-field light intensities of the femtosecond laser pulses through a subwavelength aperture

By using the method for the numerical calculation of Green's function, the light field of the femtosecond laser pulses through a subwavelength aperture is simulated and calculated.The time-dependent laser pulse with Gauss profile is decomposed into a series of monochromatic simple harmonic waves firstly.For the light field of the harmonic wave with a single frequency,the numerical calculation is made and the light fields in the space domain are received.Such numerical solution is iterated for all the waves with different frequencies,and all the numerical solutions are transformed into the light fields in the time domain by inverse Fourier transform.Through analysis,it is found that the femtosecond laser pulses propagate the both sides of the aperture along the medium interface,and during the propagating process,the diffraction light fields form the intensity nodes on the medium interface and in the near domain.