†Physical Sciences Division, ‡Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States.
Nano Lett. 2015 May 13;15(5):3472-8. doi: 10.1021/acs.nanolett.5b00803. Epub 2015 Apr 9.
We record time-resolved nonlinear photoemission electron microscopy (tr-PEEM) images of propagating surface plasmons (PSPs) launched from a lithographically patterned rectangular trench on a flat gold surface. Our tr-PEEM scheme involves a pair of identical, spatially separated, and interferometrically locked femtosecond laser pulses. Power-dependent PEEM images provide experimental evidence for a sequential coherent nonlinear photoemission process, in which one laser source launches a PSP through a linear interaction, and the second subsequently probes the PSP via two-photon photoemission. The recorded time-resolved movies of a PSP allow us to directly measure various properties of the surface-bound wave packet, including its carrier wavelength (783 nm) and group velocity (0.95c). In addition, tr-PEEM images reveal that the launched PSP may be detected at least 250 μm away from the coupling trench structure.
我们记录了从平面金表面上光刻图案化的矩形沟槽中发射的传播表面等离激元 (PSP) 的时间分辨非线性光电子发射显微镜 (tr-PEEM) 图像。我们的 tr-PEEM 方案涉及一对相同的、空间分离的、干涉锁定的飞秒激光脉冲。功率相关的 PEEM 图像为顺序相干非线性光电子发射过程提供了实验证据，其中一个激光源通过线性相互作用发射 PSP，而第二个激光源随后通过双光子光电子发射探测 PSP。记录的 PSP 的时间分辨电影使我们能够直接测量表面束缚波包的各种特性，包括其载波波长 (783nm) 和群速度 (0.95c)。此外，tr-PEEM 图像显示，发射的 PSP 至少可以在距离耦合沟槽结构 250 μm 的距离处被探测到。
