Real‐Time Arbitrary Multi‐Bit Phase Manipulation Based on 2‐Bit Digital Spoof Surface Plasmon Polaritons with 360° Phase Coverage

ABSTRACT

As a core enabling technology in modern information systems, digital phase manipulation is urgently required to deliver higher phase‐shifting accuracy and enable flexible adjustment of the modulation order. However, conventional digital phase shifters provide fixed phase‐shift values with a limited phase‐shift order, lacking the ability to realize real‐time arbitrary bit‐width extension. Here, we propose a novel phase‐shifting strategy that enables arbitrary multi‐bit phase shifting with real‐time reconfigurable bit depth using 2‐bit digital spoof surface plasmon polaritons (SSPPs). The equivalent phase‐shift vector of the proposed digital phase shifter can be represented as the superposition of phase‐shift vectors corresponding to its four discrete states. Then, 2‐bit digital SSPPs is fabricated, which yields phase shifts of 0°, 90°, 180°, and 270° in response to the control signal inputs 00, 01, 10, and 11, respectively. By applying square‐wave control signals with varying duty cycles, phase shifts with an arbitrary number of bits can be achieved, and the phase‐shifting range covers a full 360°. Experimental results demonstrate that the proposed phase shifter based on 2‐bit digital SSPPs achieves 7‐bit phase‐shifting with amplitude variation less than 3 dB. The proposed strategy offers a novel approach for the real‐time design of arbitrary multi‐bit digital phase shifters.