Adaptive subwavelength control of nano-optical fields
Adaptive subwavelength control of nano-optical fields
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DOI：
10.1038/nature05595
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发表时间：
2007-03-15
期刊：
影响因子：
64.8
通讯作者：
Steeb, Felix
中科院分区：
文献类型：
--
作者：
Aeschlimann, Martin;Bauer, Michael;Steeb, Felix
飞秒激光脉冲的相位和振幅的自适应整形已经发展成为干涉现象的直接操纵的有效工具，从而提供对各种量子力学系统的相干控制（1-10）。飞秒甚至阿秒范围内的时间分辨率已经被证明，但空间分辨率受到衍射的限制，大约为光场波长的一半（即几百纳米）。理论表明（11，12），通过纳米结构的照明可以克服相干控制的空间限制：空间近场分布被证明取决于照射激光脉冲的线性啁啾。将这一思想扩展到自适应控制，将多参数脉冲整形与学习算法相结合，证明了以最佳和灵活的方式生成用户指定的光学近场分布（13）。激光脉冲14、15的偏振的成形提供了特别有效和通用的纳米光学操纵方法（16、17）。在这里，我们通过飞秒激光脉冲的自适应偏振成形来定制银纳米结构附近的光学近场14、15，然后通过双光子光电发射电子显微镜（18）探测横向场分布，从而在实验上证明了这一概念的可行性。在自适应控制（1-10）和纳米光学（19）的这种组合中，我们实现了纳米尺度上电磁强度的亚波长动态定位，从而克服了传统光学的空间限制。这种理论建议的实验实现（11- 13，16，17，20）在相干控制，纳米光学，非线性光谱学和其他研究领域开辟了许多前景，在这些领域中，光学研究是以空间或时间分辨率进行的。
Adaptive shaping of the phase and amplitude of femtosecond laser pulses has been developed into an efficient tool for the directed manipulation of interference phenomena, thus providing coherent control over various quantum-mechanical systems(1-10). Temporal resolution in the femtosecond or even attosecond range has been demonstrated, but spatial resolution is limited by diffraction to approximately half the wavelength of the light field (that is, several hundred nanometres). Theory has indicated(11,12) that the spatial limitation to coherent control can be overcome with the illumination of nanostructures: the spatial near-field distribution was shown to depend on the linear chirp of an irradiating laser pulse. An extension of this idea to adaptive control, combining multiparameter pulse shaping with a learning algorithm, demonstrated the generation of user-specified optical near-field distributions in an optimal and flexible fashion(13). Shaping of the polarization of the laser pulse 14,15 provides a particularly efficient and versatile nano-optical manipulation method(16,17). Here we demonstrate the feasibility of this concept experimentally, by tailoring the optical near field in the vicinity of silver nanostructures through adaptive polarization shaping of femtosecond laser pulses 14,15 and then probing the lateral field distribution by two-photon photoemission electron microscopy(18). In this combination of adaptive control(1-10) and nano-optics(19), we achieve subwave-length dynamic localization of electromagnetic intensity on the nanometre scale and thus overcome the spatial restrictions of conventional optics. This experimental realization of theoretical suggestions(11-13,16,17,20) opens a number of perspectives in coherent control, nano-optics, nonlinear spectroscopy, and other research fields in which optical investigations are carried out with spatial or temporal resolution.