Tapered dielectric structure in metal as a wavelength-selective surface plasmon polariton focuser

Symmetric tapered dielectric structures in metal havedemonstrated applications such as the nanofocusing of surfaceplasmon polaritons, as well as the waveguiding of V-channelpolaritons. Yet the fabrication of smooth-surfaced tapered structureremains an obstacle to most researchers. We have successfullydeveloped a handy method to fabricate metal-sandwiched taperednanostructures simply with electron beam lithography. Though thesestructures are slightly different from conventional symmetricV-shaped structures, systematic simulations show that similarfunctionality of surface plasmon polariton nanofocusing can still beachieved. When parameters are properly selected,wavelength-selective nanofocusing of surface plasmon polaritons canbe obtained.