SPR phase detection for measuring the thickness of thin metal films

In this paper, a novel method to determine the thickness of thin metal film is put forward which uses Surface Plasmon Resonance (SPR) phase detection method. The relations between the metal film thickness and the phases of the transverse magnetic (TM) and transverse electric (TE) polarization of the reflected light are shown in the simulation results. By recording the interference patterns which contain the information of the phase differences in the experiments, the values of thickness are calculated. Both of the theoretical analysis and experimental results indicate that the approach presented is feasible and reliable. Thus, it is possible to use the method of phase detection to determine the thickness of thin metal films within 100nm in SPR prism couplers directly with nanometer resolution.