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

与位相相关的光束推动了光在各种物理过程中的应用。在这里，我们研究了利用与相位相关的ω/2ω近红外飞秒脉冲对半导体/金属纳米混合器件中的弹道电流进行相干控制。虽然这种技术是在块状半导体中建立起来的，但第一个资助期的工作证明了它们对纳米设备的适用性。特别是，在单根μ纳米线中，光感应电流高达几个GaAsA。对ω脉冲使用谐振的光学天线可以发现提高效率的充分证据。虽然我们已经在块状材料上建立了光学天线，但现在我们将把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控制。这样的方案还将允许研究与三阶光学非线性χ(3)有关的微扰区域之外的电流注入。预计在超短脉冲的强照射下，五阶贡献将变得相关，如果不是主导的话。同时，我们将致力于相干控制的新的光谱应用。本质上，电流的量子干涉控制在2个ω光组件的电场中是线性的。这样的处理与傅里叶变换光谱相结合，可以反过来用来恢复脉冲本身的相位和幅度。虽然原理验证实验已经在第一个资助期实现，但我们现在想要通过纳米工程探测器来实现光学频率的超快电场示波器。最后，我们计划充分利用这些方案的相位分辨率，展示具有幅度、相位和时间分辨率的暂态光学非线性的实验。

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.