a1 Institute of Physics, University of Münster, 48149 Münster, Germany
a2 Institute of Optics and Department of Biomedical Engineering, University of Rochester, Rochester, NY 14627, USA
The ability of metal surfaces and nanostructures to localize and enhance optical fields is the primary reason for their application in biosensing and imaging. Local field enhancement boosts the signal-to-noise ratio in measurements and provides the possibility of imaging with resolutions significantly better than the diffraction limit. In fluorescence imaging, local field enhancement leads to improved brightness of molecular emission and to higher detection sensitivity and better discrimination. We review the principles of plasmonic fluorescence enhancement and discuss applications ranging from biosensing to bioimaging.