Ultra-Broadband Signal Processing

Group Web Site

[ Professor ] Taiichi Otsuji
Ultra-Broadband Devices and Systems

[ Associate Professor ] Akira Satou
Ultra-broadband Device Physics

[ Assistant Professor ] Takayuki Watanabe

[ Research Fellow ] Victor Ryzhii

Research Activities

Terahertz (sub-millimeter) coherent electromagnetic waves are expected to explore the potential application fields of future information and communications technologies. We are developing novel, ultra-broadband integrated signal-processing devices/systems operating in the millimeter and terahertz frequency regime.

Ultra-Broadband Devices and Systems (Prof. Otsuji)

We are developing novel, integrated electron devices and circuit systems operating in the millimeter-wave and terahertz regions. III-V- and graphene-based active plasmonic heterostructures for creating new types of terahertz lasers and ultrafast transistors are major concerns. By making full use of these world-leading device/circuit technologies, we are exploring future ultra-broadband wireless communication systems as well as spectroscopic/imaging systems for safety and security.

Research topics

  • Creation of Graphene Terahertz Lasers.
  • Creation of 2D-Atomically-Thin-Layered Hetero-junctions and their Applications to Novel Terahertz Photonic Devices.
  • Physics of Graphene Dirac Plasmons and its Terahertz Functional Applications.
  • Creation of EIC (Energy-Information-Communication) Converged Resilient Network Infrastructure towards Super-Smart Society
current-injection graphene transistor laser (DFB-DG-GFET). SEM images, measured ambipolar property, simulated modal gain and Q factor, and world-first measured single-mode THz lasing spectra.
world-first observation of terahertz spontaneous emission in double-graphene-layered 2D atomically thin heterojunctions via photoemission-assisted resonant tunneling.

Ultra-broadband Device Physics (Assoc. Prof. Satou)

We are developing novel, integrated electron devices and circuit systems operating in the millimeter-wave and terahertz regions. III-V- and graphene-based active plasmonic heterostructures for creating new types of terahertz lasers and ultrafast transistors are major concerns. By making full use of these world-leading device/circuit technologies, we are exploring future ultra-broadband wireless communication systems as well as spectroscopic/imaging systems for safety and security.

Research topics

  • 2D Plasmons in Graphene and Compound-Semiconductor Heterostructures and Their Applications to Terahertz Sources and Detectors.
  • Terahertz Optical Gain in Graphene and Its Application to Terahertz Lasers.
  • Photonics-Electronics Convergence Carrier Converters.
Schematic view, SEM image, and measured mixing output of a UTC-PD-top-integrated HEMT photonics-electronics-convergence mixer.