Terahertz wide range phase manipulation with super-resolution precision by near-field nonlinear coupling of a digitally coding needle meta-chip

Abstract

Achieving ultra-precise wide-range terahertz (THz) phase modulation has been a long-standing challenge due to the short wavelength and sensitive phase of THz waves. This paper proposes a new ultra-high precision phase control method employing a digitally coding needle meta-chip embedded in a waveguide. The needle tips can effectively couple THz waves via the charge aggregation effect. By controlling the Schottky diodes with coding voltages, the charge on each meta-structure part can be tuned to form strong or weak resonances, producing phase shifts. Crucially, the massive charge accumulation and the sub-λ/10 distance between needle tips lead to near-field coupling among multiple tips. Therefore, modulation of the charge at each tip by multichannel coding voltages enables combined resonance tuning of THz waves, yielding a nonlinear phase superposition. Here, a meta-chip containing 8 needle meta-structure units is demonstrated, which breaks through the precision limitation of independent units and realizes super-resolution precision phase modulation similar to super-resolution imaging. In the 213–227 GHz band, we achieve a phase shift exceeding 180° with 11.25° accuracy, and a phase shift of over 170° with an accuracy of 3°. This super-resolution phase modulation strategy provides a new idea for future high-precision applications of THz integrated systems.