Plasmonic quadrant lens for beam-position sensing.
We present the design of a plasmonic quadrant lens (QL) which is capable of coupling the light from free space into surface plasmon polaritons (SPPs) and focusing them into four directions, depending on the polarization content of the incident light. The lens is composed of a set of uniform nanogrooves etched on a gold film. Two types of QLs with four and eight foci are realized. We further propose QLs as a plasmonic version of well-known quadrant detectors for beam-position sensing through a center location algorithm. The sensitivity of the device is also investigated for both linear and circular polarized incidences. Calculation results show that the four-focus QL offers a large effective detecting area and the eight-focus QL enables beam-position sensing to be operated with two different sensitivities simultaneously.
Jiayuan
J
Wang
Jing
J
Yang
Zhenjian
Z
Bai
Jiasen
J
Zhang