Terahertz-domain optically tunable all-dielectric doped silicon broadband absorption array

Abstract In this paper, an optically controlled all-dielectric metamaterial array is proposed based on doped silicon, consisting of a substrate and an open square ring grating. The structure achieves more than 90% absorption in the 0.7-4.12 THz range. The electric field distribution reveals the physical mechanism of efficient absorption by the combination of Fabry-Perot resonance and diffraction effect. Furthermore, since the carrier concentration is proportional to the pump fluence, the regular tuning of the absorption spectra can be realized by photoexcitation. As the pump fluence increases, the first absorption peak experiences a redshift that approximately follows an exponential function, accompanied by a gradual saturation of amplitude. Compared to previous tunable doped silicon absorbers, the design proposed by our team demonstrates superior broadband absorption performance, and the all-dielectric structure reduces the processing difficulty, providing reliable support for terahertz imaging, communication, sensing, and other applications.