Integrated multi-scheme digital modulations of spoof surface plasmon polaritons

The future wireless communications require different kinds of modulation functions to be integrated in a single intelligent device under different scenarios. Here, we propose a multi-scheme digital modulator to achieve this goal based on integrated spoof surface plasmon polaritons (SPP) in different frequency bands. By constructing switchable spoof SPP units, the propagating wave in the proposed spoof SPP waveguide can be manipulated in amplitude domain, frequency domain, and phase domain. As a proof of concept, the integrated multi-scheme digital modulator is experimentally verified to achieve at least three kinds of modulations, including amplitude shift keying, phase shift keying, and frequency shift keying, in a single digital spoof plasmonic waveguide. The simulated and measured results show that the modulator has excellent property of field confinement and is capable of frequency-domain modulation. Hence, the multi-scheme modulation property makes the proposed SPP digital modulator be an effective and reliable candidate for efficient manipulations of SPP waves and for advanced modulation technology