Koji Fujimura

A linearized method for unique determination of the input pump powers in designing and controlling WDM-pumped Raman amplifiers

We successfully developed a linearized method for predicting the multi-wavelength interactions through stimulated Raman scattering, and solved the inverse problem to uniquely determine the optimum input pump power allocation from a given target gain spectrum.

High-Temperature Thermoelectric Properties of Polycrystalline Silicon Clathrate Ba8TMxSi46−x (TM = Ni, Pt)

The n-/p-type stability of a silicon clathrate in which silicon was substituted with nickel or platinum was evaluated by density functional theory calculations. Then, Ba8Pt5Si41 and Ba8Pt1.5Ni3.5Si41 were synthesized, and their thermoelectric properties were investigated. The polycrystalline compounds, which have a type-I clathrate structure, were prepared through arc melting and spark-plasma-sintering. The crystal structures and elemental compositions of the synthesized samples were characterized via powder x-ray diffraction and electron microprobe analyses, respectively. The temperature dependence of both the electrical resistivity and the Seebeck coefficient was measured.