Polarization-tunable compact plasmonic wavelength demultiplexers based on Fano nanoantennas

Abstract

A compact plasmonic wavelength demultiplexer is an essential prerequisite for practical applications, including the next-generation on-chip devices, near-field optical trapping, and micromanipulation. However, alleviating the polarization dependence of the wavelength demultiplexers remains one of the most challenging issues in realizing such a plasmonic device. Here we propose a gold disk-slit-based compact Fano-type nanoantenna capable of launching surface plasmon polaritons (SPPs) directionally when irradiated under different wavelengths of light, realizing a wavelength demultiplexing function. More importantly, our simulation results show that the shortage of requirement of specific light polarization direction excitation in such wavelength demultiplexers can be circumvented. Furthermore, it is found that the output channel of the SPP can be switched in multiple directions under different polarization excitations. In addition, the results show that the applicable wave band of the wavelength demultiplexing device can be flexibly adjusted by changing the size of the nanoantenna. The technique of introducing the polarization-tunable function into the wavelength demultiplexers in the plasmonic interconnect application enhances the freedom of information transmission and offers a promising building block for future high-speed and high-bandwidth on-chip optical communication.