The Amplification Of Surface Plasmon Polaritons At The Interfere Between Silver Film And Gain Media

Surface plasmon polaritons (SPPs) are collective electron excitations at the interface of a metal and a dielectric. SPPs can be concentrated into subwavelength scale, thus beating the diffraction limit and offering promising prospects towards electro-opto integration on a single chip. However the intrinsic absorption of a metal in visible range leads to the decrease of the propagating length and the factor of quality. This impedes the developments and applications of SPP-based devices and systems. In the thesis, the properties of SPPs propagating along the interface of a silver film and a gain medium were studied. It is expected that the loss in the propagation of SPPs can be compensated and the amplification of SPPs can be realized through stimulated emission of gain medium under the application of a pump beam.This work will be valuable for the development of SPPs devices.The system consisting of a prism, a metal film, a gain medium film was constructed. SPPs at the interface of the silver film and the dielectric were excited by attenuated total reflection (ATR) and the properties of the SPPs were studied by the reflection. The dependence of ATR curve on the gain is studied by transfer matrix method. When the gain is larger than the loss there is a sharp peak in the reflective curve at the resonance angle and in the meanwhile the propagating length of SPPs increases with the gain.Prism/silver film/PMMA:R6G system was fabricated and ATR curves at the wavelength of 632.8nm with and without the pump beam at the wavelength of 532nm and pulse width of several nanoseconds were obtained. Under the application of the pump beam above a certain power, a peak occurred in the reflective curve and the corresponding maximal gain is 150%. This is consistent with the above theoretical results. Besides the dependence of normalized reflective intensity on the pump power, angular spectrum of gain and gain threshold were also studied.