Institut national de la recherche scientifique - Centre Energie, Matériaux et Télécommunications (INRS-EMT), 1650 Lionel-Boulet, Varennes, Québec J3X 1S2, Canada.
A*STAR Institute of High Performance Computing, Singapore 138632.
Sci Rep. 2017 Jan 10;7:40058. doi: 10.1038/srep40058.
We demonstrate an intense broadband terahertz (THz) source based on the interaction of relativistic-intensity femtosecond lasers with aligned copper nanorod array targets. For copper nanorod targets with a length of 5 μm, a maximum 13.8 times enhancement in the THz pulse energy (in ≤20 THz spectral range) is measured as compared to that with a thick plane copper target under the same laser conditions. A further increase in the nanorod length leads to a decrease in the THz pulse energy at medium frequencies (≤20 THz) and increase of the electromagnetic pulse energy in the high-frequency range (from 20-200 THz). For the latter, we measure a maximum energy enhancement of 28 times for the nanorod targets with a length of 60 μm. Particle-in-cell simulations reveal that THz pulses are mostly generated by coherent transition radiation of laser produced hot electrons, which are efficiently enhanced with the use of nanorod targets. Good agreement is found between the simulation and experimental results.
我们展示了一种基于相对论强度飞秒激光与排列整齐的铜纳米棒阵列靶相互作用的强宽带太赫兹（THz）源。对于长度为 5μm 的铜纳米棒靶，与相同激光条件下的厚平面铜靶相比，在≤20THz 光谱范围内，THz 脉冲能量最大增强了 13.8 倍。进一步增加纳米棒的长度会导致中频率（≤20THz）的 THz 脉冲能量降低，而高频范围（20-200THz）的电磁脉冲能量增加。对于后者，我们测量到长度为 60μm 的纳米棒靶的最大能量增强 28 倍。粒子模拟揭示，THz 脉冲主要是由激光产生的热电子的相干渡越辐射产生的，而使用纳米棒靶可以有效地增强这些辐射。模拟结果与实验结果吻合良好。
