Last year, the team of Sheng Zhigao, a researcher at the High Magnetic Field Center of the Hefei Institute of Physical Sciences, Chinese Academy of Sciences, developed an active and intelligent terahertz electro-optic modulator relying on the steady-state high magnetic field experimental device. The research is published in ACS Applied Materials & Interfaces.

Although terahertz technology has superior spectral characteristics and wide application prospects, its engineering application is still seriously limited by the development of terahertz materials and terahertz components. Among them, the active and intelligent control of terahertz wave by external field is an important research direction in this field.

Aiming at the cutting-edge research direction of terahertz core components, The research team has invented a terahertz stress modulator based on the two-dimensional material graphene [Adv. Optical Mater. 6, 1700877(2018)], a Terahertz broadband photocontrolled modulator based on the strongly associated oxide [ACS Appl. Mater. Inter. 12, After 48811(2020)] and phonon-based new single-frequency magnetic-controlled terahertz source [Advanced Science 9, 2103229(2021)], the associated electron oxide vanadium dioxide film is selected as the functional layer, multi-layer structure design and electronic control method are adopted. Multifunctional active modulation of terahertz transmission, reflection and absorption is achieved (Figure a). The results show that in addition to the transmittance and absorptivity, the reflectivity and reflection phase can also be actively regulated by the electric field, in which the reflectivity modulation depth can reach 99.9% and the reflection phase can reach ~180o modulation (Figure b). More interestingly, to achieve intelligent terahertz electrical control, the researchers designed a device with a novel “terahertz – electric-terahertz” feedback loop (Figure c). Regardless of the changes in the starting conditions and the external environment, the smart device can automatically reach the set (expected) terahertz modulation value in about 30 seconds.

(a) Schematic diagram of an electro optic modulator based on VO2

(b) changes of transmittance, reflectivity, absorptivity and reflection phase with impressed current

(c) schematic diagram of intelligent control

The development of an active and intelligent terahertz electro-optic modulator based on associated electronic materials provides a new idea for the realization of terahertz intelligent control. This work was supported by the National Key Research and Development Program, the National Natural Science Foundation and the High Magnetic Field Laboratory Direction Fund of Anhui Province.