Showing papers by "Jong Heo published in 2011"
TL;DR: In this article, a series of tellurite glasses were selected and their third-order optical nonlinearities (TONL) were measured by employing the Z-scan method at a wavelength of 800 nm with femtosecond laser pulses.
Abstract: Tellurite glasses from TeO2–Bi2O3–BaO pseudo-ternary system were prepared using a conventional melt-quenching method and its glass-forming region was determined. A series of glasses were selected and their third-order optical nonlinearities (TONL) were measured by employing the Z-scan method at a wavelength of 800 nm with femtosecond laser pulses. The results showed that glass former Te4+ ions exhibited positive influences on the TONL and glass modifiers Ba2+ ions behaved similarly; low concentrated Bi3+ ions as glass modifiers weakened the nonlinearities, but an excess amount of Bi3+ behaved oppositely. FTIR measurements demonstrated that chemical bonds especially Te–Oeq vibrated at a high energy level remarkably promoted the TONL susceptibility χ(3), and the glass sample with the highest Bi2O3 content exhibited the largest χ(3) value which was due to the presence of BiO3 polyhedra.
45 citations
TL;DR: In this paper, Ellipsoidal gold nanoparticles embedded bismuthate glasses have been prepared via a facile melt-annealing approach, and femtosecond Z-scan measurement shows that the nanocomposites exhibit a maximum third-order nonlinear susceptibility χ (3) of 4.88 × 10 −10 −10 ǫ at 800nm, which is two orders higher than that of the host glass.
34 citations
TL;DR: In this paper, heat-treatment was used to precipitate PbS quantum dots (QDs) in silicate glasses doped with different amounts of Ag 2 O, and the influence of ag 2 O on QDs was investigated under given heat treatment conditions.
Abstract: Heat-treatment was used to precipitate PbS quantum dots (QDs) in silicate glasses doped with different amounts of Ag 2 O, and the influence of Ag 2 O on QDs was investigated Under given heat-treatment conditions, the absorption coefficients and photoluminescence intensities of PbS QDs increased with the addition of Ag 2 O Ag clusters formed by thermal treatment nucleated formation of PbS QDs in glasses
25 citations
TL;DR: In this article, a chalcohalide glass with a composition of 65GeS2-25Ga2S3-10CsI (in mol%) doped with 0.6 wt% Tm3+ ions was prepared by conventional melt-quench method.
Abstract: Chalcohalide glass with a composition of 65GeS2-25Ga2S3-10CsI (in mol%) doped with 0.6 wt% Tm3+ ions was prepared by conventional melt-quench method. By heat treating the precursor glass at 20 °C above its glass transition temperature Tg for different durations, IR transparent glass ceramics were obtained. X-ray diffraction (XRD) and scanning electron microscope (SEM) showed that Ga2S3 crystallites were precipitated after heat treatment and their grain sizes were in nano-scale and increased with the elongation of heat treated time. Mid-IR luminescence properties of the glass and transparent glass ceramic samples were investigated. The emissions at 2.3 and 3.8 μm corresponding to optical transitions of 3H4 → 3H5 and 3H5 → 3F4 of Tm3+ ions were significantly enhanced by the presence of Ga2S3 nanocrystals and reached a maximum after 8 hours treatment.
23 citations
TL;DR: In this paper, X-ray diffraction and scanning electron microscope studies confirmed the formations of Ga 2 S 3 and GeS 2 phase grains with sizes of 2-5 and 80-nm, respectively.
Abstract: Chalcohalide glass-ceramics based on GeS 2 –Ga 2 S 3 –CsCl pseudo-ternary system were prepared by heat treatment method. X-ray diffraction and scanning electron microscope studies confirmed the formations of Ga 2 S 3 and GeS 2 phase grains with sizes of 2–5 and 80 nm, respectively. Z-scan technology was employed to investigate the third-order nonlinear optical characteristics of both precursor glass and its glass ceramics at 800 nm. The results show that nonlinear refractive index n 2 as well as nonlinear absorption coefficient β increase after heat treatment, which is due to quantum effects, and the largest n 2 of the glass ceramics is 4.3 × 10 − 11 esu which is 4 times larger than that of the host.
19 citations
TL;DR: In this article, the influence of Ag on photoluminescence (PL) of CdS QDs was investigated, and the emission located at 478-493nm in wavelength originated from the direct recombination of electron/hole pairs.
Abstract: Silicate glasses containing CdS and Ag2O were made by the melt-quenching method. CdS quantum dots (QDs) were precipitated inside the glass matrix by heat treatment at 570–590 °C for 10 h, and the influence of Ag on photoluminescence (PL) of CdS QDs was investigated. The emission located at 478–493 nm in wavelength originated from the direct recombination of electron/hole pairs was quenched due to charger transfer between Ag and CdS QDs. Modification of PL from CdS QDs by Ag provides potentials toward developing the color changing materials for light-emitting diodes (LEDs).
18 citations
TL;DR: In this article, the compositional dependence of blue emission from Nd 3+ /Tm 3+ co-doped Ge-Ga-S-CsBr chalcohalide glasses was investigated.
Abstract: Mechanisms of the compositional dependence of blue emission from Nd 3+ /Tm 3+ co-doped Ge–Ga–S–CsBr chalcohalide glasses were investigated. The blue upconversion emissions (centered at 475 nm) due to the Tm 3+ : 1 G 4 → 3 H 6 transition decreased as the CsBr/Ga ratio in glasses while the other upconversion emissions from the Nd 3+ ions increased. Changes in the local environment of rare-earth ions incurred by the CsBr addition significantly increased the excited state absorption within Nd 3+ ions. This resulted in the decrease in the Nd 3+ → Tm 3+ energy transfer rates that led to the large decrease in blue upconversion emission.
17 citations
TL;DR: In this paper, a series of silver (Ag0) nanoclusters embedded in bismuthate glasses (Bi2O3-B2O 3-TiO2) were synthesized by the thermochemical reduction method.
Abstract: A series of silver (Ag0) nanoclusters embedded in bismuthate glasses (Bi2O3-B2O3-TiO2) were synthesized by the thermochemical reduction method. When B2O3 was substituted with TiO2, the refractive index of the encapsulating medium increased, leading to redshifting of the surface plasmon resonance (SPR) absorption band of Ag0, which was initially located at 612 nm. Z-scan measurements with femtosecond laser pulses at 800 nm showed that third-order optical nonlinearities (TONs) were significantly enhanced in the SPR redshifted samples, and calculation of the figure of merit manifested excellent performances of present Ag0-bismuthate nanocomposites for TON-based all-optical switching.
15 citations
TL;DR: In this article, the absorption and emission spectra for the 3 H 4 ↔( 3 F 2, 3 H 6 ) transition of Pr 3+ ions embedded in Ge-Sb-Se glasses were analyzed and shown to change systematically upon the introduction of a small amout of Ga.
7 citations
TL;DR: In this article, a detailed study on near-infrared and midinfrared fluorescence emissions with five sets of Tm3+-doped 75GeS2-15Ga2S3-10CsI chalcohalide glass is presented.
Abstract: This work presents a detailed study on near-infrared and mid-infrared fluorescence emissions with five sets of Tm3+-doped 75GeS2–15Ga2S3–10CsI chalcohalide glass. They are prepared in normal or water drying process. Based on the diffusion-limited relaxation calculation, a detailed investigation is put forward to obtain efficient near-infrared or mid-infrared fluorescence emissions of Tm3+ on the effect of H2O on the Tm3+ fluorescence. Detailed investigations are given to the interacted energy transferring processes between rare-earth, impurities and vibrating phonons with the appearance of fluorescence quenching, along with Tm3+, H2O concentrations varying and energy gaps forming. The radioactive properties are analyzed using compensated diffusion-limited relaxation calculation method, and the near-IR and mid-IR fluorescence properties are evaluated in detail with experimental and theoretical analysis.
3 citations
TL;DR: In this article, a series of (100 − x)-GeTe4.3 − xCdI2/ZnI2 far infrared transmitting glasses were prepared by traditional melt-quenching method and the allowed indirect transition optical band gap was calculated according to the classical Tauc equation.
Abstract: A systematic series of (100 − x)(GeTe4.3) − xCdI2/ZnI2 far infrared transmitting glasses were prepared by traditional melt-quenching method. ZnI2 (20 mol%) can be introduced in the glassy matrix, while only 10 mol% CdI2 can be incorporated in the Ge-Te-CdI2 glass system. Based on differential thermal analysis (DTA) data, most of the glass samples have good thermal stability. A maximum ΔT value of 115 °C was obtained for the glass composition 90(GeTe4.3)–10ZnI2. The allowed indirect transition optical band gap was calculated according to the classical Tauc equation. It is found that the indirect optical band gap decreased from 0.619 to 0.569 eV with the CdI2 addition and increased from 0.628 to 0.677 eV with the ZnI2 addition. According to infrared transmission spectra, the Ge-Te-CdI2/ZnI2 glasses show wide IR transparency.