Time-resolved optical measurement of thermal transport by surface plasmon polaritons in thin metal stripes

We investigate the thermal transport originating from the propagation of surface plasmon polaritons (SPPs) in a thin gold stripe. The SPPs are excited by a grating coupler on the Au stripe which was patterned onto a silicon membrane. The transmissivity changes of the Si membrane due to temperature-induced changes of the interference conditions enable measuring the temperature distribution with temporal and spatial resolution better than 1 μs and 1 μm. With this setup, we demonstrate that SPP excitation, propagation, and decay are accompanied by considerable heating and heat transport.