A research group led by Prof. SHENG Zhigao from the Hefei Institutes of Physical Science (HFIPS) of the Chinese Academy of Sciences (CAS) has investigated an active and smart Terahertz (THz) electro-optic modulator. Related results were published in ACS Applied Materials & Interfaces.
Terahertz technology has attracted extensive attention in recent years due to its wide applications in imaging, communication, medicine and security. These applications drive the urgent need for high-performance THz devices. Active and smart THz modulators are urgent requirement for intelligent THz beam scanning, automatic terahertz imaging, etc.
In this study, the researchers proposed this active and smart THz electro-optic modulator based on vanadium dioxide (VO2) film. In addition to transmission and absorption, it can also electrically modulate the reflection and phase of THz waves.
By utilizing an electric current-induced insulator-to-metal transition in the VO2 film, the researchers achieved near-perfect antireflection (99.9% modulation depth) and 180° phase switching. Smart electro-optic THz control was realized in the VO2 structure by using a “THz-electro-THz” geometry feedback loop.
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, using strongly correlated electron material, has opened up avenues for the realization of THz smart devices.
This work was supported by the National Key Research and Development Program of China, the National Natural Science Foundation of China and the High Magnetic Field Anhui Provincial Laboratory Fund.