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. One example is the frequency-tunable plasmon-resonant terahertz emitters, detectors, and modulators. Another example is unique electromagnetic metamaterial circuit systems based on optoelectronic dispersion control of low-dimensional plasmons. We are also pursuing graphene-based new materials to create new types of terahertz lasers and ultrafast transistors, breaking through the limit on conventional transistor/laser operation. 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.

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

For creation of millimeter-wave/terahertz devices based on new materials and/or new operation principles, we are theoretically and experimentally investigating physics in the devices such as electron-transport phenomena and optoelectronic properties. Furthermore, we are conducting research and development of the devices for their applications to future ultra-fast wireless communications and photonics-electronics convergence networks.

(Upper left: 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.
Upper right: world-first observation of terahertz spontaneous emission in double-graphene-layered 2D atomically thin heterojunctions via photoemission-assisted resonant tunneling.
Lower: Operation principle, SEM image, and measured detector responsivity of an asymmetric dual-grating-gate InP high-electron-mobility transistor.)