Recently, a research group led by Prof. SHENG Zhigao from High Magnetic Field Laboratory, Hefei Institutes of Physical Science (HFIPS) of Chinese Academy of Sciences (CAS) investigated an active and smart Terahertz electro-optic modulator.
Related results were published in ACS Applied Materials & Interfaces.
Terahertz (THz) technology, for its promising applications in the fields of imaging, communication, medicine, and security, attracted considerable attention in recent years. These applications drived urgent needs for high-performance THz devices. Among them, active and smart THz modulators were highly desired to realize smart THz beam scanning, automatic THz imaging and other smart applications.
In this study, the researchers proposed an active and smart THz electro-optic modulator based on VO2 film. It standed out with many advantages.
Besides the transmission and the absorption, it could electrically modulate the reflection and phase of THz waves.
By utilizing an electric current induced IMT in VO2 film, the team achieved near-perfect antireflection (99.9% modulation depth) and 180o phase switching. By utilizing a feedback loop of "THz-electro-THz" geometry, they also realized smart electro-optic THz control in the VO2 structure.
The desired THz amplitude could be achieved accurately no matter what the initial condition was and how the external environment changed.
This proposed electro-optic THz modulation method, taking advantage of strongly correlated electron material, opened up avenues for the realization of THz smart devices.
This work was supported by the National Key Research and Development Program, the National Natural Science Foundation and the High Magnetic Field Anhui Provincial Laboratory Fund.
(a) Schematic diagram of active THz electro-optic modulator based on VO2 film. (b) Experimental transmission (T), reflection (R), absorption (A) and reflection phase shift (?φ) as a function of applied electric current at 0.55 THz. (c) Schematic diagram of smart THz manipulation. (Image by REN Zhuang)