Generation of coherent radiation in the IR and terahertz ranges during the propagation of a multi-terawatt laser pulse along a nanowire target is investigated. In the process of interaction, dense electron bunches are displaced from the target and accelerated in the laser field, generating intense electromagnetic radiation. Three regimes of interaction can be realised depending on the duration and shape of the laser pulse. In the first regime, when the laser pulse is long enough (tens and hundreds of femtoseconds), electrons are only partially forced out of the target. The characteristics of the low-frequency part of the spectrum of the generated radiation are determined in this case by the duration of the laser pulse, as well as by its amplitude and target parameters (geometric dimensions and concentration of electrons). In the second regime, the laser pulse has a large amplitude and a steep rising edge (the amplitude of the first half-wave is of the order of the maximum pulse amplitude); as a result, most of the electrons are displaced from the target already at the initial moment of interaction. In this regime, unipolar and bipolar pulses with a duration of tens of laser field periods can be formed. Changing the target length makes it possible to control the period of field oscillations and their number in the generated radiation. In the intermediate regime of short laser pulses with an insufficiently steep rising edge, oscillations of the formed electron bunches can occur in the macroscopic Coulomb attraction field of the charged target, which gives rise to radiation with a frequency several times lower than that of laser radiation. In this case, the pulses of the generated radiation contain a few cycles of the field with decreasing amplitude and increasing frequency. Using numerical simulation in three regimes of interaction, the characteristics of IR and terahertz radiation are found, in particular, the pulse shapes, ranges of generated frequencies, amplitudes and angular distributions of radiation are determined. It is shown that the amplitude of the generated pulse can reach subrelativistic and relativistic values (the field strength is more than 1 TV m⁻¹ at a frequency ten times lower than the laser radiation frequency), and the energy conversion efficiency can be of the order of one percent.

研究了在多太瓦激光脉冲沿纳米线目标传播期间在 IR 和太赫兹范围内产生相干辐射。在相互作用的过程中，密集的电子束从目标物上移开并在激光场中加速，产生强烈的电磁辐射。根据激光脉冲的持续时间和形状，可以实现三种相互作用机制。在第一种情况下，当激光脉冲足够长（数十和数百飞秒）时，电子仅部分被迫离开目标。在这种情况下，所产生辐射频谱的低频部分的特性由激光脉冲的持续时间以及其幅度和目标参数（几何尺寸和电子浓度）决定。在第二种制度中，激光脉冲幅度大，上升沿陡（前半波幅度为最大脉冲幅度量级）；结果，大多数电子在相互作用的初始时刻就已经从目标上转移了。在这种情况下，可以形成持续时间为数十个激光场周期的单极和双极脉冲。改变目标长度可以控制场振荡的周期及其在产生的辐射中的数量。在上升沿不够陡峭的短激光脉冲的中间状态下，所形成的电子束会在带电目标的宏观库仑引力场中发生振荡，从而产生频率比激光辐射低几倍的辐射. 在这种情况下，产生的辐射脉冲包含几个场周期，幅度减小，频率增加。使用三种相互作用机制的数值模拟，发现了红外和太赫兹辐射的特性，特别是确定了脉冲形状、产生的频率范围、幅值和辐射角分布。结果表明，产生的脉冲幅度可以达到亚相对论和相对论值（场强大于1 TV m 确定辐射的幅度和角度分布。结果表明，产生的脉冲幅度可以达到亚相对论和相对论值（场强大于1 TV m 确定辐射的幅度和角度分布。结果表明，产生的脉冲幅度可以达到亚相对论和相对论值（场强大于1 TV m^-1频率比激光辐射频率低十倍），能量转换效率可以达到百分之一。