Akiyama, Hidefumi

Biography

Advanced laser spectroscopy on the basis of lasers and microscopy is developed and applied to semiconductor quantum wires and other nano-structures, in order to understand and control their optical properties quantum mechanically. Femto-second pulse generation directly from gain-switched semiconductor lasers is studied intensively to understand the pulse dynamics and the shortest-pulse limit. High-quality III-V-semiconductor tandem solar cells and their internal loss rates and mechanisms are also studied. We make the world thinnest and cleanest quantum-wire semiconductor lasers that have superior laser performances such as low threshold currents. Experimental findings and problems provide us fruitful physics subjects related to 1D physics, many-body physics, lasers, solar cells, crystal growth, material science, and semiconductor device physics and engineering. We are developing experimental techniques such as sensitive luminescence detection, absolute luminescence-yield measurements, transmission/absorption measurements of single nano-structures, micro-spectroscopy, imaging, and solid-immersion microscopy. Some of these techniques have been applied to study of bioluminescence of fireflies, jelly fish, and sea fireflies as well as luminol chemiluminescence.

Research Interest

Device physics of gain-switched semiconductor lasers and solar cells Many-body interactions and non-equilibrium properties of low-dimensional electron-hole systems in clean semiconductor quantum wires and wells Material physics and development of high-quality semiconductor nano-structures via microscopy Bioluminescence of firefly, jelly fish, sea firefly, etc. and bio/chemiluminescence measurement standards