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| RESEARCH ACTIVITIES |
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| Porous Glass based Visible and Near-infrared Emitting Materials
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180. Sa chu rong gui, Kenji Imakita, Minoru Fujii, Zhenhua Bai, and Shinji Hayashi,
"Near Infrared Photoluminescence from Bismuth-Doped Nanoporous Silica Thin Films",
Journal of Applied Physics, Vol. 114, Issue 3, 033524, pp. 1–5 (2013). (Copyright (2013) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. )
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| Photoluminescence (PL) properties of bismuth (Bi) doped porous silica thin
films annealed at various temperatures and in different atmospheres were
studied. The near infrared (NIR) luminescence depended strongly on the
annealing atmosphere and temperature. To reveal the origin of the NIR luminescence,
we performed comprehensive PL studies including steady state and time-resolved
PL measurements at 8–300 K in wide excitation (250–500 nm) and detection
(400–1550 nm) wavelength ranges. It was revealed that multiple Bi luminescence
centers, such as Bi3+, Bi2+, Bi+, and Bi dimer, are stabilized in porous
silica. |
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159. Sa chu rong gui, Kenji Imakita, Minoru Fujii, Zhenhua Bai, Shinji Hayashi,
Luminescence properties of Bi-doped oxidized porous silicon thin films
Optical Materials, Vol. 34, pp. 1161-1164 (2012).
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| Luminescence properties of Bi-doped oxidized porous silicon (OPS)
thin films were studied. It was found that this material shows two broad
luminescence bands centered at 845 nm with the FWHM of 120 nm and at 1410
nm with that of 220 nm under 488 nm excitation. A detailed analysis of
the 3D plot of PL intensities versus excitation and emission wavelengths
revealed that these luminescence bands arise from at least two different
kinds of Bi luminescence centers. The broad luminescence covering the whole
telecommunication window (1.2–1.6 μm) suggests that Bi-doped OPS thin films
can be a candidate material for a broadband waveguide-type optical amplifier
at optical telecommunication wavelengths. |
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55. E. Gross, D. Kovalev, N. Künzner, J. Diener, F. Koch, and M. Fujii,
"Stimulated Light Emission in Dense Fog Confined inside a Porous Glass Matrix,”
Physical Review Letters, Vol. 89, No. 26, 267401, pp. 1-4, December (2002). |
| We report on light amplification through stimulated emission in a dielectrically
disordered medium. Liquid fragments confined in the solid matrix of porous
quartz layers result in a random fluctuation of the dielectric function,
and dye molecules embedded in the voids yield optical gain. The level of
opacity is tunable by the ambient vapor pressure of the dielectric substance.
In the multiple scattering regime, a strong intensity enhancement of the
dye emission accompanied by significant spectral narrowing is observed
above the threshold for a layer being in the opalescence state. |
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