SURFACE PLASMON ENHANCED PHOTOLUMINESCENCE ON BIHARMONIC GRATING STRUCTURE

We compare the fluorescence enhancement from a conducting polymer film placed on top of a sinusoidal and biharmonic metallic grating. On the biharmonic grating, which possesses a surface plasmon polariton band-gap, the enhancement factor was larger than that on a sinusoidal grating, even though the coupling efficiency of the surface plasmon polariton was lower for the biharmonic grating. We investigate the mechanism of fluorescence enhancement numerically by finite difference time domain analyses and attribute the larger fluorescence enhancement to the electric field of the short wavelength band-edge mode extending longer into the dielectric region where the fluorophore is placed.