Danckwerts Matthias, Novotny Lukas
Institute of Optics, University of Rochester, Rochester, New York USA.
Phys Rev Lett. 2007 Jan 12;98(2):026104. doi: 10.1103/PhysRevLett.98.026104. Epub 2007 Jan 10.
We present nonlinear-optical four-wave mixing (4WM) at coupled gold nanoparticles. By decreasing the interparticle distance from large separation to touching contact, the 4WM yield increases by 4 orders of magnitude. The reason for this dramatic enhancement lies in the shift of the localized plasmon resonance to infrared wavelengths as the dimer is formed, making one of the input wavelengths doubly resonant. At the touching point, the 4WM signal changes discontinuously because of a sudden charge redistribution imposed by the formation of a conductive bridge. The 4-wave mixing signal provides an ultrasensitive measure for the contact point between a pair of particles and it can be employed as a spatially and temporally controllable photon source.
我们展示了耦合金纳米颗粒中的非线性光学四波混频（4WM）。通过将粒子间距离从大间距减小到接触，4WM产率增加了4个数量级。这种显著增强的原因在于，随着二聚体形成，局域表面等离子体共振向红外波长移动，使得其中一个输入波长产生双共振。在接触点处，由于导电桥形成导致的电荷突然重新分布，4WM信号会发生不连续变化。四波混频信号为一对粒子之间的接触点提供了一种超灵敏测量方法，并且它可以用作空间和时间上可控的光子源。
