Dual-Field Superfocusing Through Steering Hybrid Evanescent Modes

In this paper, a sort of dual-field superfocusing is demonstrated with a plasmonic array based on metal waveguides. A theory of steering hybrid evanescent modes is used to design the plasmonic array. Both electric and magnetic fields are converged to a focus spot at a distance of 0.11. The full widths at halfmaximum (FWHMS) of the two fields are 0.04λ and 0.069λ with the superfocusing metrics of 2.5 and 1.45. Dual-field superfocusing is beneficial for super-resolution imaging, extreme subwavelength lithography, and noncontact sensing.