Adaptive control of tip-enhanced near-field optical signals in carbon nanotubes

超快激光光谱学能够实时观测光诱导过程，并在阿秒时间尺度上探索其动力学和反应路径。通过整形超短激光脉冲的光谱幅度和相位，甚至可以相干地控制电子和振动激发态的贡献。最优控制是通过使用学习环技术的自适应脉冲整形、微调分支比和反应产率来实现的。另一方面，近场光学的目标是超越目前衍射到10 nm左右的传统显微镜的分辨率极限。我们提出了一种将超快自适应控制和针尖增强近场光学显微镜(UAC-TENOM)相结合的新技术，该技术以碳纳米管为模型纳米结构。具体地说，我们将利用偏振整形激光脉冲实现对可调谐金属粒子构型的近场干扰和脉冲压缩的自适应控制。将超高速自适应控制和TIP增强技术相结合，通过进一步提高TENOM的空间分辨率和信号增强，提供了实质性的附加值。我们的结果将形成对单个纳米结构中激发态的完全时空和相干控制的重要步骤，并将对其他纳米尺度的光谱产生重大影响。

Ultrafast laser spectroscopy enables real time observations of photo-induced processes and the exploration of their dynamics and reaction pathways on attosecond time-scales. By shaping the spectral amplitude and phase of ultrashort laser pulses the contributing electronically and vibronically excited states can even be controlled coherently. Optimum control is achieved by adaptive pulse shaping using learning-loop techniques fine-tuning branching ratios and reaction yields. Near-field optics, on the other hand, aims at surpassing the resolution limit of conventional microscopy imposed by diffraction reaching about 10 nm at present. We propose to develop a novel technique by combining ultrafast adaptive control and tip-enhanced near-field optical microscopy (UAC-TENOM) using carbon nanotubes as model nanostructures. Specifically, we will achieve the adaptive control of near-field interference and pulse compression in tunable metal-particle configurations using polarization shaped laser pulses. Merging ultrafast adaptive control and tip-enhanced techniques offers substantial added value by further increasing spatial resolution and signal enhancement of TENOM. Our results will form important steps towards full spatio-temporal and coherent control of excited states in single nanostructures and will have a major impact on other nanoscale spectroscopies.