从实验上研究了光电导天线电极之间激光光斑大小对太赫兹波产生的影响。另外，理论模拟了激光功率密度与太赫兹波辐射强度之间的关系，与实验结果非常吻合。泵浦光激光功率密度的增加能够显著的提高太赫兹波辐射强度，但是当超过一定值后会趋于饱和，此时若继续减小光斑尺寸，激光功率密度的增加不会使太赫兹产生继续增强。但是，太赫兹波却会随着光斑尺寸的减小而变弱。

It was experimentally investigated that the laser spot size on photoconductive antenna(PCA) gap could have a great influence on terahertz(THz) generation. Moreover, the simulation on THz generation influenced by the laser power density was carried out, which was agreed well to the experiments. It is well demonstrated that the increase of laser power density on PCA gap can enhance THz generation. However, the intensity of THz radiation reached saturation while the laser power density exceeding a certain value. The laser power density increased further by focusing harder, but the THz radiation was getting weaker due to the smaller laser excited area on PCA gap.