Excitation of molecular fluorescence via surface plasmon polaritons

The intensity of photoluminescence from a thin layer of laser dye on a metallic grating depends on the polarization and angle of incidence of the incident beam of light. For an appropriate polarization and angle of incidence, the beam can resonantly excite surface plasmon polaritons (SPPs). The dye layer experiences a much enhanced optical field and so absorbs more energy, and the fluorescence emission intensity is consequently enhanced. Experimental results are presented demonstrating an increase by a factor of 9–9 in the fluorescence yield. A novel technique for numerical modelling of the system is presented and, having established the validity of the model, is used to determine how the enhancement depends on the sample parameters.