Leakage radiation microscopy of surface plasmon polaritons

We review the principle and methodology of leakage radiation microscopy (LRM) applied to surface plasmon polaritons (SPPs). Therefore we first analyze in detail the electromagnetic theory of leaky SPP waves. We show that LRM is a versatile optical far-field method allowing direct quantitative imaging and analysis of SPP propagation on thin metal films. We illustrate the LRM potentiality by analyzing the propagation of SPP waves interacting with several two-dimensional plasmonic devices realized and studied in the recent years.