Optical coherent control of electrical currents in semiconductor-metal hybrid nanostructures: physics and spectroscopic applications

相位相关的光束已经推进了光在各种物理过程中的应用。本文研究了半导体/金属混合纳米器件中弹道电流的相干控制问题。虽然这种技术是在大块半导体中建立的，但第一个资助期的工作表明它们适用于纳米器件。特别地，在单个GaAs纳米线中光诱导出高达几μA的电流。使用谐振ω脉冲的光学天线发现了提高效率的实质性证据。虽然我们已经在大块材料上建立了光学天线，但我们现在将联合收割机这种结构与纳米线和纳米管相结合，以展示对电流的有效深亚波长光学控制。这样的方案也将允许研究超出与三阶光学非线性相关的微扰区域的电流注入。预计在超短脉冲的强辐照下，5阶贡献将变得相关，如果不是主导的话。同时，我们将致力于相干控制的新光谱应用。本质上，电流的量子干涉控制在2ω光分量的电场中是线性的。与傅里叶变换光谱学相结合的这种过程可以相反地用于检索脉冲本身的相位和幅度。虽然在第一个资助期内已经实现了原理验证实验，但我们现在希望对探测器进行纳米工程设计，以实现光学频率下的超快电场探测器。充分利用这些计划的相位分辨率，我们最终计划演示实验的瞬态光学非线性振幅，相位和时间分辨率。

Phase-related optical beams have advanced the application of light in a broad variety of physical processes. Here, we study coherent control of ballistic electrical currents in hybrid semiconductor/metal nanodevices with phase-related ω/2ω near-infrared femtosecond pulse pairs. While such techniques are established in bulk semiconductors, the work of the first funding period has demonstrated their applicability to nanodevices. In particular, electrical currents as large as several μA are optically induced in single GaAs nanowires. Substantial evidence for an improved efficiency is found using optical antennas resonant for the ω pulse. While we have established optical antennas on bulk materials, we now will combine such structures with nanowires and nanotubes to demonstrate efficient deep sub-wavelength optical control of electrical currents. Such schemes will also permit to study current injection beyond the perturbative regime related to a third-order optical nonlinearity χ(3). It is expected that 5th order contributions will become relevant if not dominant under strong irradiance with ultrashort pulses. In parallel, we will work on novel spectroscopic applications of coherent control. In essence, quantum interference control of electrical currents is linear in the electric field of the 2ω light components. Such processes in combination with Fourier transform spectroscopy can conversely be utilized to retrieve phase and amplitude of the pulse itself. While proof-of-principle experiments have already been realized in the first funding period, we now want to nanoengineer detectors to realize ultrafast electric field oscilloscopes at optical frequencies. Taking full advantage of the phase-resolution of such schemes, we finally plan to demonstrate experiments on transient optical nonlinearities with amplitude-, phase, and time-resolution.