Ultrafast multi-terahertz nano-spectroscopy with sub-cycle temporal resolution
Ultrafast multi-terahertz nano-spectroscopy with sub-cycle temporal resolution
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DOI：
10.1038/nphoton.2014.225
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发表时间：
2014-11-01
期刊：
影响因子：
35
通讯作者：
Hober, R.
中科院分区：
文献类型：
--
作者：
Eisele, M.;Cocker, T. L.;Hober, R.
在丰富的太赫兹光谱范围（1-18）中的锁相超短脉冲为量子限制（7），一阶相变（8，12），高温超导（11）和纳米材料中的载流子传输（1，6），（13-15）等各种现象提供了关键的见解。对少周期场瞬变的超宽带电光采样（1）甚至可以揭示比光的单个振荡周期发生得更快的新颖动态（4，8，10）。然而，传统的太赫兹光谱学本质上受限于衍射极限的系综测量。因此，它可以测量纳米颗粒、纳米晶体或纳米畴的尺寸、结构、取向和密度的平均介电函数。在这里，我们将超宽带时间分辨太赫兹光谱扩展到亚纳米颗粒尺度（10 nm），通过将子周期，场分辨检测（10 fs）与散射型近场扫描光学显微镜（s-NSOM）（16-26）相结合。我们追踪了单个光激发InAs纳米线表面在所有三个空间维度上随时间变化的介电函数，揭示了超快（
Phase-locked ultrashort pulses in the rich terahertz spectral range(1-18) have provided key insights into phenomena as diverse as quantum confinement(7), first-order phase transitions(8,12), high-temperature superconductivity(11) and carrier transport in nanomaterials(1,6),(13-15). Ultrabroadband electrooptic sampling of few-cycle field transients(1) can even reveal novel dynamics that occur faster than a single oscillation cycle of light(4,8,10). However, conventional terahertz spectroscopy is intrinsically restricted to ensemble measurements by the diffraction limit. As a result, it measures dielectric functions averaged over the size, structure, orientation and density of nanoparticles, nanocrystals or nanodomains. Here, we extend ultrabroadband time-resolved terahertz spectroscopy to the sub-nanoparticle scale (10 nm) by combining subcycle, field-resolved detection (10 fs) with scattering-type near-field scanning optical microscopy (s-NSOM)(16-26). We trace the time-dependent dielectric function at the surface of a single photoexcited InAs nanowire in all three spatial dimensions and reveal the ultrafast (