大尺寸太赫兹平顶波束的产生研究

Generation of large-size terahertz flat-topped beam

为了实现低频段太赫兹高斯波束整形为大尺寸平顶波束,提出了一种利用双相位板结构设计大尺寸平顶波束整形系统的方法。基于Input-Output算法,利用角谱理论计算系统参数,同时对所设计系统进行了数值仿真并搭建了实验系统,验证了出射光场的横向强度分布是否符合预期。结果表明,所设计的双相位板整形系统能够成功将0.1 THz高斯波束转换为百毫米尺寸的平顶波束,仿真结果与理论较为接近,证明了设计系统的合理性。实验中波束直径达到228 mm,虽存在部分能量泄漏,但是平坦程度很好,相对均方根甚至优于理论和仿真结果,可达89%以上,充分说明了设计方法的有效性。

For the purpose of shaping the low frequency terahertz Gaussian beam into the large-size flat-topped beam,a method of designing a large-size flat-topped beam shaping system using dual-phase plate structure was proposed.Based on the Input-Output algorithm,the system parameters were calculated using angular spectrum theory,and the designed system was numerically simulated and the corresponding experimental system was built to verify whether the lateral intensity distribution of the emitted light field met expectations.The results show that the designed dual-phase plate shaping system can successfully convert the 0.1 THz Gaussian beam into a 100 mm-size flat-topped beam.The simulation results are close to the theory,which proves the rationality of the designed system.In the experiment,the beam diameter reaches 228 mm.Although there is some energy leakage,the flatness is very good,and the relative root mean square is even better than the theoretical and simulation results,reaching more than 89%,which fully demonstrates the actual effectiveness of this design method.