Nanophotonics using a subwavelength aperture in a metal film

This review focuses on the optical theory and applications of a single subwavelength aperture in a metal film. We begin with Bethe's aperture theory for the optical transmission through a subwavelength aperture in a perfect electric conductor film and extend the discussion to apertures in real metals of finite thickness and to apertures with different shapes. Extraordinary optical transmission (EOT) is reviewed, particularly for an aperture in a transverse waveguide screen and for waveguide EOT with applications to aperture near-field probes. We overview applications of single subwavelength nanoapertures to refractive index sensing, single molecule fluorescence detection, Raman spectroscopy and optical trapping of dielectric nanoparticles, including biological matter. Finally, we discuss the potential of combining these many different capabilities to create greater functionality with a single aperture.