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Akiyama Group

Research Associate

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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.

Nano-structures of a 100 T-shaped quantum-wire laser (a,b) and firefly luciferase protein (c) .
Direct 4.7 ps pulse generation from a gain-switched semiconductor laser diode.

Research Subjects

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