| AVS 60th International Symposium and Exhibition | |
| Nanometer-scale Science and Technology | Monday Sessions |
| Session NS+BI+EM-MoM |
| Session: | Nanophotonics and Plasmonics |
| Presenter: | H. Petek, University of Pittsburgh |
| Correspondent: | Click to Email |
We study surface plasmon polariton (SPP) generation, propagation, diffraction, interference, focusing, and decay by femtosecond time-resolved photoemission electron microscopy (PEEM) and electromagnetic simulations. Equal-pulse pump-probe pulses with interferometrically defined delay excite two-photon photoemission from Ag surfaces. The imaging of the spatial distribution of photoemitted electrons by PEEM reveals a nonlinear map of the total surface electromagnetic fields impressed on the sample. On a nanostructured surface the images reveal coherent polarization gratings consisting of superposition of the incoming excitation pulses and propagating SPP wave packets that are generated at nanofabricated coupling structures. By changing the delay between the pump and probe plusses in steps of ~330 as we record movies of the evolving coherent polarization at the Ag/interface, which reflects the evolution of the surface electromagnetic fields. Through the combination of femtosecond laser excited photoemission and imaging of photoelectrons we can record <10 fs time scale coherent polarization dynamics with ~50 nm spatial resolution. [1]
The SPP fields are generated by specifically designed coupling structures formed by lithographic techniques in Ag films. The physical properties of the coupling structures and the geometry of the excitation define the subsequent SPP dynamics. To obtain a quantitative understanding of the SPP generation and PEEM imaging we perform FDTD calculations on the coupling of the external field into the SPP mode and compare them to experiments for slit coupling structures with different geometries. [4] Using more complicated coupling structures, we demonstrate SPP interference and focusing. [5] Through time-resolved PEEM measurements on nanostructured metal films we will explore the techniques for the coherent control of electromagnetic fields in nanostructured electronic materials on the femtosecond temporal and nanometer spatial scales.
References
[1] A. Kubo, K. Onda, H. Petek, Z. Sun, Y. S. Jung, and H. K. Kim, Nano Lett. , 1123 (2005).
[2] A. Kubo, N. Pontius, and H. Petek, Nano Lett. , 470 (2007).
[3] A. Kubo, Y. S. Jung, H. K. Kim, and H. Petek, J. Phys. B: , S259 (2007).
[4] L. Zhang, A. Kubo, L. Wang, H. Petek, and T. Seideman, Phys. Rev. B , 245442 (2011).
[5] H. Petek and A. Kubo, in Handbook of Instrumentation and Techniques for Semiconductor Nanostructure Characterization, Haight, R.; Ross, F.; Hannon, J., Eds. World Scientific Publishing/Imperial College Press: 2011.