Tailoring the emission polarization with metasurface-based emitters designed on a plasmonic ridge waveguide.

Because of low propagation losses and flexible communication paths, inter-chip optical communications based on plasmonic emitters and receivers can overcome the obstacle of the inherent ohmic loss in metallic nanostructures. To increase the communication capacity and integration density in inter-chip optical communications, we propose to tailor the polarization states of the free-radiation fields from the emitters in both the spectral domain and spatial domain by designing the phased and polarized arrangement of subwavelength metallic nanogroove antennas on a two-dimensional plasmonic ridge waveguide. Herein, the utilization of the two-dimensional plasmonic waveguide with tight field confinements considerably decreases the crosstalk to nearby plasmonic devices in plasmonic circuits and chips. In the spectral domain, three different polarization states of the free-radiation fields from the same emitter are experimentally realized at three specific wavelengths. In the spatial domain, the different polarization states as well as the gear polarization states are experimentally demonstrated. Moreover, the separation of the adjacent polarization-tailoring plasmonic emitters is only 5% of that in dielectric emitters because of the ultra-compact size (<0.6λ2) of metasurface-based plasmonic emitters.