A Programmable Amplitude and Phase Modulator Based on Spoof Surface Plasmon Polaritons

ABSTRACT A programmable amplitude and phase modulator based on spoof surface plasmon polaritons (SSPPs) is presented for miniaturized applications. The presented compact passive SSPPs unit cell has a lower asymptotic frequency than the conventional SSPPs one. To reach the same asymptotic frequency with the demonstrated compact passive SSPPs unit cell, the conventional SSPPs unit cell would require a larger width. The size of the demonstrated compact passive SSPPs structure is only 59.30% of the conventional SSPPs one. More importantly, based on the compact passive SSPPs structure with meander line, we further investigate a compact active SSPPs unit cell. The programmable modulator exhibits four key functions: amplitude modulation, bandwidth tuning, digital phase shifting and “AND” logic gate. The amplitude can be individually modulated by switching an electrically tuned attenuator (ETA). Specifically, the maximum modulation depth is 34.3 dB. A prototype of the SSPPs‐based programmable modulator is fabricated and assembled. The measured results are in excellent agreement with simulated ones. In conclusion, this work provides innovative solutions in unit design, miniaturization, multifunctionality, and large‐range amplitude modulation for SSPP‐based devices. The demonstrated programmable modulator shows promising potential in the multifunctional integrated circuits, plasmonic devices, and advanced communication and radar systems.