Splitting and radiation of a surface plasmon by resonant ionization in a thin semiconductor coating

Time evolution of a surface plasmon guided by a metal surface owing to rapi d ionization in a thin semiconductor film placed on the metal surface is th eoretically investigated. When the plasma frequency of the created plasma i n the film is close to the frequency of the initial surface plasmon, plasma oscillations in the film are resonantly excited by the surface plasmon, an d the energy of the initial surface plasmon starts to move back and forth b etween these oscillations and the surface plasmon. Initially fast surface p lasmons also produce significant transient radiation that propagates from t he metal surface into vacuum. The general picture of transient processes th at occur after ionization can be applied for ultrafast transient spectrosco py of an electron-hole plasma in metal and semiconductor films. (C) 2001 Op tical Society of America.