Indiana-based University of Notre Dame scientists have discovered graphene’s ability to effectively modulate the terahertz band, a part of the electromagnetic spectrum.
Terahertz radiation that lies between the lowest energy infrared light and the highest energy radio waves pave way for exciting new possibilities in chemical detection, medical imaging and communications. It is very difficult to produce, modulate and identify terahertz waves. Adjusting the height or modulation of the terahertz waves is significant as a modulated signal is capable of transmitting information and is more suitable for biological and chemical sensing applications.
Tiny semiconductor transistor-like structures form the basis of current high-potential terahertz technologies as modulation of a terahertz signal at room temperature is possible using these tiny structures. This is significant as previous modulators were able to function only at exceedingly cold temperatures. However, these transistor-like units depend on a thin metal layer known as a ‘metal gate’ to modulate the terahertz signal. This metal gate considerably decreases the strength of the signal and modulates up to 30%.
According to the findings published in Applied Physics Letters, a journal of the American Institute of Physics, by using a single graphene layer in place of the metal gate, the scientists have expected that the range of modulation can be considerably increased to more than 90%. Modulation control is possible by voltage application between the semiconductor and graphene. Unlike the metal gate design, the graphene-based modulator barely reduces the terahertz energy’s output power.
Source: http://www.aip.org