Optical modulation processes in thin films based on thermal effects of surface plasmons

Experimental results are presented for light-on-light modulation at low rates using coupling to nonradiative surface plasmons and their associated thermal effects in a thin gold foil. It is first shown that several modulated Gaussian beams simultaneously exciting surface plasmons in the same region of a thin gold film, will result in a coupling that is revealed in the reflected beams. The observed effects result in the reflected beams undergoing changes in both spatial distribution and intensity levels. A brief study is then presented of the coupling between surface plasmons and an electrical current in the excitation region to further support the role of the surface plasmon induced thermal processes in the gold foil.