Symmetric tapered dielectric structures in metal have demonstrated applications such as the nanofocusing of surface plasmon polaritons,as well as the waveguiding of V-channel polaritons.Yet the fabrication of smooth-surfaced tapered structure remains an obstacle to most researchers.We have successfully developed a handy method to fabricate metal-sandwiched tapered nanostructures simply with electron beam lithography.Though these structures are slightly different from conventional symmetric V-shaped structures,systematic simulations show that similar functionality of surface plasmon polariton nanofocusing can still be achieved.When parameters are properly selected,wavelengthselective nanofocusing of surface plasmon polaritons can be obtained.
