MTL News Archives for 2014

New Core Faculty: Ruonan Han

September 4, 2014

MTL welcomes Prof. Ruonan Han. An expert in Teraherz electronics, he aims to bridge the "Teraherz gap"

ruonan_han.jpgProfessor Ruonan Han joined the EECS department at MIT as an assistant professor in July. He has also joined MTL as a core member and as a resident member with his office in Building 39. He received his B.Sc. degree in microelectronics from Fudan University in 2007 and his M.Sc. degree in electrical engineering from the University of Florida in 2009. In 2014, he received the Ph.D. degree in electrical and computer engineering (ECE) from Cornell University, where he also won the ECE Innovation Award and the Director's Best Thesis Research Award. Professor Han's research is focused on high-performance integrated circuits and systems operating at 0.1 to 1 THz (1 THz=1000 GHz) and beyond.

Terahertz wave is opening up tremendous opportunities with its unique radiation properties. The non-ionizing imaging will flourish in biomedical diagnosis such as skin cancer detection and burn injury assessment. Spectroscopy in terahertz can play an important role in drug detection, breath analysis, etc. High-speed signal transmission and processing will also benefit from the application of this ultra-broadband spectrum. However, this frequency range is too high for classical electronics and too low for photonics, thus stays almost unexplored.

Fully-CMOS-compatible terahertz transceivers will enable ultra-high-speed data exchange between chips through free space or dielectric waveguides. This may help solve the deteriorating bandwidth-bottleneck problems in cloud computing infrastructures. Image, Ruonan Han.

At MIT, Professor Han's Terahertz Integrated Electronics Group will investigate microelectronic approaches to bridge such long-standing THz Gap. Microchips, especially those implemented in silicon, are conventionally considered to be incapable of operating at such high frequency. For example, the cut-off frequency (fmax) of transistors in mainstream CMOS technologies is still below 300 GHz. To meet the challenge, Prof. Han's research consolidates non-linear device optimization, distributed circuit design and electromagnetic engineering into these chips, and significantly enhances the THz signal generation power, detection sensitivity, as well as the circuit energy efficiency. Based on these, his group will develop highly integrated, non-intrusive imaging systems, spectrometer-on-chip, Tera-scale data link, etc. These efforts not only help us understand and utilize the properties of electronics under extremely high frequency conditions, but will also revolutionize the electronic infrastructures for communication and biomedicine.

In the future, terahertz chip can be integrated into handheld equipment, which enables vision through objects. High-power THz radiation utilizes GaN devices provided by GaN-on-Si technology or multi-chip hybrid packaging. The wallet image shown is obtained from an 280GHz imaging array by Prof. Han.