New Research


2010/07/01

Exploring New Electromagnetic-wave Regions toward Practical Applications

-Communications and Sensing Using Radio waves of the Future-

Professor:Tadao Nagatuma, Associate Professor:Junichi Takahara, and Assistant Professor: Shintaro Hi

 Since the discovery and practical use of electro-magnetic waves in the late 19th century and early 20th century, human beings have continued to utilize the electromagnetic waves in various fields such as communications, sensing, measurement, energy, healthcare, etc. In particular, an FTTH (Fiber-To-The Home) and a cellular phone are supported by “optical and/or light-wave” and “microwave and/or radio wave” communications technologies, respectively, both of which have been given rise to in the latest quarter century. The electromagnetic waves at frequencies from 100 GHz to 10 THz, which are located between light-wave and microwave frequencies, are referred to as “terahertz waves”. Terahertz waves have recently attracted great interest, since they only remain undeveloped in the 21st century.
 Our research aim is to develop generation and detection technologies for terahertz waves using our original approach, which combines microwave and light-wave (photonics) technologies, and to build practical systems for communications and sensing.
 Two examples of our most recent applications are shown below. First application is a wireless communication with a world-record data rate. By using 300-GHz carrier frequency, we have succeeded in the data transmission at a bit rate of 14 Gbit/s, which is more than 100 times higher than that of a cellular phone. Photo of transmitter and receiver modules is shown in the figure. Second application is an imaging of objects. Plastics, papers and cloths are transparent at terahertz frequencies, and some materials absorb terahertz waves at specific frequencies. We conducted the imaging as follows; a paper, on which letters are written with an Indian ink, is put into the envelope. By focusing 1.4 THz waves on the envelope, we measured the power of transmitted waves. Letters can be clearly seen by the imaging. X-ray cannot do this, since the penetration of X-ray is too strong. In addition to the above examples, numerous industrial applications of terahertz waves have been expected. We will continue our challenges towards real-world terahertz applications, which should be brought to the marketplace as early as possible.

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