Mapping of surface plasmon polariton fields by time-resolved photoemission electron microscopy: experiments, simulations, and applications

In this thesis, the static and dynamic properties of propagating surface plasmon polaritons (SPPs) are investigated. SPPs are collective electronic oscillations at the interface between a metal and a dielectric which can be excited by light. The emerging field of nanoplasmonics has attracted much attention over the last decades. The unique properties of SPPs make them interesting not only for fundamental research, but also for technological applications. Applications range from broadband data transmission confined by subwavelength nanowires to sensing applications which are e. g. used in the medical sector. For instance, it has recently been shown that the analysis of the frequency shift of SPP resonances can be applied for the determination of human blood groups. There has been particular high interest in the fundamental research of SPPs intended for use in improving the energy efficiency of solar cells. For all applications, a thorough understanding of the processes involved is indispensable. Therefore, several methods have been developed for the observation of the manifold properties of SPPs. In this work, the method of photoemission electron microscopy (PEEM) is applied. It provides a parallel imaging scheme of the photoelectron distribution which is emitted from a conducting surface when illuminated with light. This distribution is modified by the existence of SPPs due to the near field interference with the exciting electromagnetic field. Static effects as well as dynamic effects are observed by using ultrashort laser pulses. For the examination of dynamic effects, an interferometer which enables time-resolved measurements is applied. The development of a physical model which is able to describe the recorded PEEM image and the underlying surface plasmon dynamics is the main objective of this thesis. For this purpose, a simulation algorithm which exploits basic physical principles was developed. Not only the observed two-dimensional PEEM signal can be simulated with this method, but also the underlying dynamic effects of the SPP.