a Department of Physics and Electronic Information Engineering, Minjiang University, Fuzhou 350108, China; b College of Photonic and Electronic Engineering, Fujian Normal University, Fuzhou 350007, China
Abstract A tunable infrared plasmonic polarization filter is proposed and investigated in this paper. The filter is based on the sandwich absorption structure which consists of three layers. The top layer is an array of asymmetrical cross resonator. The middle and bottom layers are dielectric spacer and metal film respectively. By absorbing specific wavelength of the incident light perfectly, the reflection spectrum of the structure shows filter performance. The calculated results show that the absorption wavelength is strongly dependent on the length of branch of the asymmetrical cross resonator which is parallel to the light polarization and independent of the length of the vertical one. Therefore, the asymmetrical cross resonator filter structure opens the way for freely tuning the filtering wavelength for a different light polarization. We can fix a resonant wavelength (absorption wavelength) corresponding to one polarization and change the resonant wavelength for the other polarization by adjusting the corresponding branch length of the asymmetrical cross resonator, or change the two resonant wavelengths of both two polarizations at the same time.
Fund: Project supported by the National Natural Science Foundation of China (Grant Nos. 61178089 and 51277091) and the Natural Science Foundation of Fujian Province, China (Grant No. 2013J05095).
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