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Decreasing the threshold current density in Si lasers fabricated by using dressed-photons

100%

Tanaka H., Kawazoe T., Ohtsu M., Akahane K.

Fluorescent Materials

2015

vol. 1

issue 1

We fabricated a silicon (Si) laser by applying a dressed-photon–phonon assisted annealing process to a ridge-type light waveguide that we fabricated via siliconon- insulator (SOI) technology. We also evaluated a nearinfrared Si photodiode having optical gain to estimate the differential gain coefficient for designing lightwaveguides. We designed light waveguides having a thickness of 15 μm to realize a large optical confinement factor. The fabricated Si laser oscillated at a wavelength of 1.4 μm. The intensity of amplified spontaneous emission (ASE) lightwas too low to be observed, because the threshold current density was so low that the Si laser started oscillating immediately after ASE occurred. The threshold current density for oscillation was estimated to be 40 A/cm2 from the current– voltage characteristic. This threshold current density was twenty-eight times smaller than that of a Si laser we fabricated previously.

Coarse Aggregate Recycling by Pulsed Discharge Inside of Concrete

52%

Inoue S., Araki J., Aoki T., Maeda S., Iizasa S., Takaki M., Wang D., Namihira T., Shigeishi M., Ohtsu M., Akiyama H.

In Japan, the treatment of waste concrete scraps has been one of the environmental issues. Therefore, new application using pulsed power discharge has been developed as the recycling method of the coarse aggregates from the waste concrete scraps. In the work, the dependences of the quality of the recycled coarse aggregate by the repetitive pulsed discharge treatments on the consumption energy were investigated. As the results, it was clear that the quality of the recycled coarse aggregate could be controlled by the number of discharge treatments. The recycled coarse aggregate, which satisfied class H under the regulations of Japan Industrial Standard (JIS A5005 and JIS A5021), was produced with the smallest consumption energy when the discharged energy from 0.02 μF of capacitor charged up to 400 kV applied to the waste concrete scraps during single discharge treatment.

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1 Acta Physica Polonica A

1 Fluorescent Materials

1 2015

1 2009

2 Ohtsu M.

1 Akahane K.

1 Akiyama H.

1 Aoki T.

1 Araki J.

1 Iizasa S.

1 Inoue S.

1 Kawazoe T.

1 Maeda S.

1 Namihira T.

1 Shigeishi M.

1 Takaki M.

1 Tanaka H.

1 Wang D.

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Decreasing the threshold current density in Si lasers fabricated by using dressed-photons

Coarse Aggregate Recycling by Pulsed Discharge Inside of Concrete