Savoini Matteo, Grübel Sebastian, Bagiante Salvatore, Sigg Hans, Feurer Thomas, Beaud Paul, Johnson Steven L
Opt Express. 2016 Mar 7;24(5):4552-4562. doi: 10.1364/OE.24.004552.
Generation of high intensity terahertz radiation in the low frequency region (f < 5 THz) is still a challenging task and only few experimental demonstrations exceeding 1 MV/cm have been reported so far. One viable option is the use of resonant metallic structures which act as amplifiers for the impinging radiation. Here with the aid of finite difference time domain simulations, we design and realize a set of isolated resonant elements which allow us to reach a 28-fold enhancement of freely propagating THz radiation at f ≈ 1 THz. These elements are deposited on a GaP sample allowing the direct measurement of the field enhancement using electro-optical sampling. Interestingly, we experimentally show strong modifications of the antennas resonance which is interpreted in terms of interference effects. These are particularly important in samples thinner than half the spatial pulse length.
在低频区域（f < 5太赫兹）产生高强度太赫兹辐射仍然是一项具有挑战性的任务，到目前为止，仅有少数超过1兆伏/厘米的实验演示报道。一种可行的选择是使用共振金属结构，其可作为入射辐射的放大器。在此，借助时域有限差分模拟，我们设计并实现了一组孤立的共振元件，这使我们能够在f ≈ 1太赫兹时将自由传播的太赫兹辐射增强28倍。这些元件沉积在磷化镓样品上，可使用电光采样直接测量场增强。有趣的是，我们通过实验表明天线共振有显著变化，这可根据干涉效应来解释。在厚度小于空间脉冲长度一半的样品中，这些干涉效应尤为重要。
