A Design Method for a Micron-Focusing Plasmonic Lens Based on Phase Modulation
- 204 Downloads
A design method of a micron-focusing plasmonic lens is proposed, which consists of a nanoaperture surrounded by concentric annular grooves with fixed width and depth. The phase modulation of the radiation lights decoupled from surface plasmon polariton waves by the annular grooves is realized by altering the radii of the grooves. Based on the principle of the constructive interference, a design formula of a micron-focusing plasmonic lens is deduced. The transmitted fields through the designed plasmonic lenses are numerically simulated with finite-difference time-domain method, and the results show that a circular focusing spot is generated where the focal length can be controlled in several micrometers, which agree with our theoretical analysis.
KeywordsSurface plasmon polaritons Subwavelength aperture Scattering light Focusing
This work is supported by the National Natural Science Foundation of China under Grant 60678028. The authors are grateful to Qingyan Wang at Peking University for theoretical discussions.