Abstract: Transparent fresnoite(Ba2TiSi2O8) glass-ceramics considered as a new type of non-linear
optical materials have been prepared by controlled heat treatment in the system
xK2O-(33.3-x)BaO-16.7TiO2-50SiO2(0≤x≤20 mol%), and optical properties were investigated. The
glassy nature was analyzed by differential thermal analyses. The transparency of glass-ceramics was
variable and controllable by the processing parameters like time and temperature. The transparent
glass-ceramics showed second harmonic generation (SHG) when irradiated by a 1064nm laser beam
(Nd:YAG). The SHG intensity was compared with a Y-cut α-quartz plate.
Abstract: In this paper we report on the effects of variables in thermal resistance measurement of high
power GaN-based light-emitting diodes (LEDs). The investigated variables include ambient
temperature, thermal interface material (TIMs) at different pressure. The combination of transient
thermal measurement method and optical measurement was employed for the study. The measured
thermal resistance of LED packages was found to increase with the ambient temperature. The
temperature dependence of optical efficiency, forward voltage, and thermal properties of packaging
materials are thought to be responsible for the increase of thermal resistance with the ambient
temperature. The interface effect on the thermal resistance was studied by applying different external
pressure on the interface with different TIMs. And the measured thermal resistances were found to
reach stabilization at certain pressure level after initial decrease with the external applied pressure.
Abstract: 70TeO2-30WO3 glass thin films were fabricated using radio-frequency magnetron
sputtering method and the effects of processing parameters on the growth rate, the surface
morphologies, the crystallinity, and refractive indices of thin films have been investigated using
AFM, XRD, SEM, and UV-Vis-IR spectrometer. Amorphous glass thin films with surface
roughness of 4~6 nm could be formed only at room temperature and crystalline WO3 phase was
observed in all the films prepared at above the room temperature. The deposition rate strongly
depended on the processing parameters. It increased with increasing rf power and with decreasing
processing pressure. Especially, it changed remarkably as varying the Ar/O2 gas flow ratio from
40sccm/0sccm to 0sccm/40sccm. When the films were formed in pure Ar atmosphere it shows a
deposition rate of ~0.2 μm/h, whereas ~1.5 μm/h when the films was formed in pure O2
atmosphere. The refractive indices of TeO2-WO3glass thin films could be measured to be about
1.849~2.165 depending on the wavelength in the range of 500-1100 nm and the bandgap energy of
glass thin film was ~3.34 eV.
Abstract: The efficient detection method based on nanostructured photonic DBR PSi has been
developed for DMMP, which is a simulant for G-type nerve agents. The manufactured DBR PSi
chip exhibits a sharp photonic band gap at 520 nm. The detection method involves the shift of DBR
peak in reflectivity spectra under the exposure of vapors of analyte. Rapid detection has been
achieved in few seconds, in situ, and observed by the red-shift of DBR peak resulted from the
increase of refractive indices in DBR PSi. When DBR PSi chip is exposed to DMMP, TEP, and
DEEP-saturated air, DBR peak in reflectivity is red shifted by 10 nm, 25 nm, and 10 nm,
respectively. Real-time detection for the nerve gases indicates that the measurement is reversible.
Detection limit of DMMP (1.5 ppm) using DBR PSi is 8.8 mg/m3 for 1 min.
Abstract: The nanostructural and optical features of Al-doped Si thin films, which were prepared by
co-sputtering Al-chips and a Si main target, were investigated in terms of Al-doping and
post-deposition heat-treatment conditions; the heat treatment was carried out at temperatures of 400 ~
1100 °C. The structural and chemical features are related with the photoluminescence (PL)
phenomena of the films. The PL intensity as well as the concentration of Si nanocrystallites were
increased by doping particular amount of Al in the films.
Abstract: We have synthesized a Eu2+-activated Sr3MgSi2O8 blue phosphor and (Sr,Ba)2SiO4 yellow
phosphor. We fabricated a phosphor-conversion white light emitting diode(LED) using an InGaN
chip that emits 400 nm near-ultraviolet(n-UV) light and phosphors that emit in the blue and yellow
region. When the white LED was operated at a forward-bias current of 20 mA at room
temperature(RT), the color temperature(Tcp), average color rendering(Ra), operating voltage(Vf) and
luminous efficacy(ηL) were estimated to be 5800K, 72.08, 3.4V, and 7.61 lm/W, respectively. The
commission International de I’Eclarirage(CIE) chromaticity coordinates obtained from the measured
spectra remained almost constant during the forward-baias current increase from 0.5 mA to 60 mA.
Abstract: Inductively coupled plasma reactive ion etching of Ge doped silica glasses and SiON was
investigated, using C2F6- and NF3-based gas mixtures. Mesas with smooth surfaces and vertical
sidewalls were obtained, with a maximum etch rate of about 310nm/min in the case of C2F6 RIE of
Ge-SiO2 and 280 nm/min in the case of SiON. The NF3 plasma yielded slightly higher etch rate,
although sloped sidewalls were obtained. Results of the X-ray photoelectron spectroscopy showed
little contamination on the etched surfaces.
Abstract: In this paper, we present the imaging parameters and compare both mercuric iodide (HgI2)
and amorphous selenium (a-Se) films. Using MCNPX code, we designed the film structure and its
thickness for the optimized detector in the diagnostic x-ray range. The mercuric iodide film was
formed by a wet binder process, while the amorphous selenium film was deposited by physical vapor
deposition (PVD). These deposition methods are capable of being scaled up to sizes required in
diagnostic imaging applications. The electronic properties are investigated using dark current, x-ray
sensitivity and signal to noise ratio (SNR). From our results, the developed HgI2 film as an alternative
to a-Se photoconductor, which is in practical use in flat panel x-ray imaging detector, will prove its
usefulness in the future design and the optimization for various diagnostic modalities.
Abstract: We have synthesized a Eu2+-activated lanthanide co-doped Sr3SiO5 : Eu yellow-orange
phosphor. In this experiment, sample powder has been synthesized by conventional solid state
method. It was calculated that luminescent efficiency of a Gd3+ co-doped Sr3SiO5:Eu phosphor
sample is up to 105% than that of only Sr3SiO5:Eu phosphor. Those samples can be applied such as
phosphor for white LED lamps through integrating on the UV or blue chips. On the contrary, the use
of a Dy, Ce, Pr and lanthanide short of Gd by the co-doping materials was caused by decreasing
luminescent intensity. The emission band was shifted from 572nm to short wavelengths by co-doping
lanthanide. The emission band of a Nd3+ co-doped Sr3SiO5 : Eu phosphor sample was not symmetrical
at 570nm. As Nd3+ concentration increased, two emission bands were observed
Abstract: Si and Er co-doped SiO2 films were fabricated by radio-frequency (RF) magnetron
sputtering technique with a Si-Er-SiO2 target. The optical gain of 0.7 dB/cm was confirmed by the
direct pumping of Er3+ using the laser diode (LD) of 980 nm in wavelength and 60 mW in output
power. On the contrary, the pumping Si-nanocrystals by the Hg lamp 365 nm (1.5 W/cm2) induced the
absorption loss above 1.48 μm region in wavelength, which was attributed to the free carrier
absorption of Si-nanocrystals.