Multi-layer Dielectric/metal-nanoparticles Construction With Broadband Perfect Absorption And Its Application In Metal Enhanced Fluorescence

Due to the unique surface plasmon resonances(SPRs)properties,Metallic nanostructures can induce a lot of novel physical effect.In this paper,we mainly study the modulation of the fluorescence enhancement and absorption enhancement from localized surface plasmon resonances(LSPRs)in the Metallic nanostructures.The main contents of our study are as follows:First,we fabricate the plasmonic broadband absorber by stacking multiple metallic nanoparticle layers through combination of the conventional physical vapor deposition technology and the thermal annealing technology.We systematically study the effect of the thickness of dielectric film,the initial film thickness of the upper Au nanoparticles and the number of the composite layer on optical properties of our absorber.In the end,we obtain the plasmonic broadband absorber which posseses the nearly perfect 700nm-broadband absorption over 95%from 400nm to 11 OOnm.Second,we study the fluorescence enhancement effect of fluorophore from the plasmonic broadband absorber.we find that due to the field enhancement effect of LSPRs and the existence of metal nanoparticles on the surface can increase the total radiation decay rate of fluorescent molecules,the emitted intensity of fluorescent molecules increase,the intensity of the PL signal from the plasmonic broadband absorber can achieve to dozens of times of the fluorescence intensity from planar Ag.when we modulate LSPRs of the metallic nanostructures to match with the emission spectrum of fluorescent molecules,it will get the strongest fluorescence enhancement effect.At the same time,We also study the fluorescence enhancement effect of fluorophore from the plasmonic broadband absorber with the different thickness of dielectric film on top of its surface.Analysis reveals that the periodic fluorescence enhancement is the optical interference fluorescence enhancement effect,and the emerging interference model can improve the molecular fluorescence excitation rate,enhancing the fluorescence intensity.Meanwhile,due to the uniformity of the plasmonic broadband absorber fabricated with our process is integral,our plasmonic broadband absorber has large potential applications and advantage.