Doped Chalcohalide Glasses Research Articles

2.5–5.5 μm mid‐infrared emission from Ni2+‐doped chalcohalide glass ceramics containing CsPbI3 perovskite nanocrystals

AbstractThe development of mid‐infrared (MIR) broadband tunable lasers urgently needs high performance laser gain materials. Transition metal (TM) ions doped glass ceramics are considered to be efficient MIR broadband laser gain media. However, it is difficult to achieve gain because of the large scattering loss and low luminescence efficiency. In this paper, GeS2–Sb2S3–CsI–PbI2 chalcohalide glass ceramics containing CsPbI3 perovskite nanocrystals are fabricated by the melt‐quenching method and subsequent heating treatment. The crystallization behavior of CsPbI3 nanophase and MIR luminescence properties of Ni2+ dopant are systematically investigated. Evidently, spherical CsPbI3 perovskite nanocrystals are precipitated and uniformly distributed in the glassy matrix, which can reduce the light scattering and make the chalcohalide glass ceramics have a high transparency. Moreover, an ultra‐broadband MIR emission in the range of 2.5–5.5 μm is observed for the first time, to our best knowledge, from Ni2+‐doped chalcohalide glass ceramics containing CsPbI3 perovskite nanocrystals. The newly developed Ni2+‐doped chalcohaldie glass ceramics could be promising gain media for MIR broadband tunable lasers.

Mid-infrared luminescence of Dy3+-doped Ga2S3–Sb2S3–CsI chalcohalide glasses**Project supported by the National Natural Science Foundation of China (Grant Nos. 61405080 and 61575086), Jiangsu Collaborative Innovation Centre of Advanced Laser Technology and Emerging Industry, China, and the Priority Academic Program Development of Jiangsu Higher Education Institutions, China.

The mid-infrared (MIR) luminescent properties of Dy3+ ions in a new chalcohalide glass host, Ga2S3–Sb2S3–CsI, are investigated; and the suitability of the doped glass for MIR fiber lasers is evaluated. The Dy3+-doped chalcohalide glasses exhibit good thermal stability and intense MIR emissions around 2.96 μm and 4.41 μm. These emissions show quantum efficiencies (η) as high as ∼ 60%, and have relatively large stimulated emission cross sections (σem). The low phonon energy (∼ 307 cm−1) of the host glass accounts for the intense MIR emissions, as well as the high η. These favorable thermal and emission properties make the Dy3+-doped Ga2S3–Sb2S3–CsI glasses promising materials for MIR fiber amplifiers or lasers.

Upconversion Luminescence of Er3+ Doped Chalcohalide Glasses and the Potential Application for Si Solar Cell Efficiency Enhancement

Er doped Ge-Ga-S-CsBr chalcohalide glasses were fabricated by melt-quenching method. The properties of upconversion luminescence under the excitation of 1550 nm laser were investigated. Strong green emissions centered at 525 nm and 545 nm, and weak red emission centered at 660 nm, were observed, along with near infrared emission bands centered at 810 nm and 980 nm. The up-conversion fluorescence was contributed to multi-photon involved process. The Si solar cell efficiency slightly increased from 7.28% (without upconversion layer) to 7.32% (using Er doped 0.9(Ge25Ga10S65)-0.1CsBr glass as upconversion layer). The results show that the investigated Er-doped chalcohalide glasses has a potential application for the enhancement of Si solar cell efficiency.

White upconversion luminescence generation from Ho3+ singly doped chalcohalide glasses

Bright white light which compose of blue, green and red emission bands from Ho3+ single doped Ge–Ga–S–CsCl (CsBr) chalcohalide glasses under 900nm infrared laser excitation were observed and investigated. The calculated color coordinates proved that the light were close to the natural sunlight. The low phonon energy of the local surrounding of Ho3+ ions and short ultra-violet cut-off edge resulted in the strong blue emission, as well as the enhanced green and red upconversion luminescence. It was also found that color coordinates of these white lights were independent on the excitation intensity. The result indicated that Ho3+ ions singly doped chalcohalide glass can be promising candidate for white light source, 3-dimensional display or color tunable visible laser.

Crystallization mechanism and optical properties of Nd3+ doped chalcohalide glass ceramics

Nd3+-doped GeS2–In2S3–CsCl transparent chalcohalide glass ceramics containing In2.67S4 nanocrystals are prepared by melt-quenching and subsequent heating. The influence of Nd3+ doping on the In2.67S4 crystallization, the microstructure, as well as the transmission and photoluminescence spectra of glass ceramics are investigated. It is proposed that Nd3+ ions act as nucleating agents for In2.67S4 crystallization in the sample with relative low Nd3+ concentration, while a part of Nd3+ ions are believed being expelled from the crystallized regions and aggregate on the surfaces of the crystallites during crystallization when Nd3+ concentration is increased, which suppresses crystal growth, resulting in nano size and homogeneous distribution of grains, and subsequently remarkable blue-shift of the optical absorption edge of the glass ceramic. Evidently, the microhardness of chalcohalide glass is strengthened after the precipitation of In2.67S4 nanophase.

Tm3+-Doped Chalcohalide Glass for Optical Amplifiers at 1.22 and 1.47 µm

50GeSe2–25In2Se3–25CsI chalcohalide glass was prepared with the addition of Tm3+ in 0.1–1.0 wt % concentrations. Radiative parameters evaluated by the Judd–Ofelt analysis suggest a strong covalence nature of the host. Emissions peak at 1.22 and 1.46 µm were observed with the 808 nm laser excitation. The 1.22 µm one is attributed to the Tm3+:3H5→3H6 transition. The Raman spectra of the host suggest that the I-rich local environment of Tm3+ promotes the strong 1.22 µm emission. The emission intensity comes to the maximum at Tm3+ concentration of 0.7 and 0.5 wt % for the 1.22 and 1.47 µm emissions respectively. In addition, its potential application as the host material for novel optical amplifiers was discussed.

Tm3+-Doped Chalcohalide Glass for Optical Amplifiers at 1.22 and 1.47 µm

Tm³⁺-Doped Chalcohalide Glass for Optical Amplifiers at 1.22 and 1.47 µm

Photoluminescence of Mn2+ Centers in Chalcohalide Glasses

We report on photoluminescence from Mn2+-doped chalcohalide glasses of the GeS2–Ga2S3–CsCl system. Upon blue excitation at 447 nm, a broad emission band occurs in the green spectral range from 500 to 600 nm, indicating the presence of tetrahedrally coordinated Mn2+ species. When the Mn2+-concentration is increased up to 2 mol%, an increasingly intense secondary emission band evolves at about 610–660 nm. Meanwhile, the intensity of the green band decreases gradually and shifts toward the red, resulting a very flatten luminescence from 500 to 750 nm, which provides a promising white light emitting source. As for the origin of this unique luminescence behavior of Mn2+, it is proposed that the ligand coordination number of Mn2+ in the present chalcohalide glasses experiences a partial change from tetrahedral to octahedral coordination.

Upconversion luminescence properties of Er3+ doped GeS2-Ga2S3-KCl chalcohalide glasses

Er3+ ions doped chalcohalide glasses with the composition of 56GeS2-24Ga2S3-20KCl were fabricated by a melt-quenching method. Under 800 nm laser excitation, strong green emissions centered at 525 nm and 550 nm and weak red emission centered at 660 nm were observed, which were assigned to 2H11/2→4I15/2, 4S3/2→4I15/2, and 4F9/2→4I15/2 transitions, respectively. The intensity reached maximum when the Er3+ ions concentration was 0.1 mol%. The possible upconversion luminescence mechanism was proposed from the discussion on the above results as well as the results of lifetimes of the metastable 4I13/2 level and local environment of Er3+ ions. It is found that chalcohalide glass can be good host materials for upconversion luminescence.

Luminescence behaviors of the Eu 2+ ions in the GeS 2-Ga 2S 3-CsCl chalcohalide glasses

In the paper, we report the luminescence behaviors of Eu 2+-doped chalcohalide glasses. Composition of glass matrix is 37.5GeS 2-22.5Ga 2S 3-40CsCl (mol%) with the concentration of Eu 2+ in the range of 0.1–0.25 (mol%). The optimal Eu 2+ doping concentration was 0.15 mol% at which the glass exhibited an enhanced emission peaking at 434 nm with a full width at half maximum (FWHM) about 80 nm with the excitation at 395 nm.

Infrared luminescence of Tm3+-doped chalcohalide glasses in GeS2–In2S3–CsBr system

Abstract Tm 3+ -doped GeS 2 –In 2 S 3 –CsBr chalcohalide glasses are presented and their infrared luminescence properties at S-band are investigated. Composition of glass matrix is 70GeS 2 –10In 2 S 3 –20CsBr (mol%) with the concentration of Tm 2 S 3 in the range of 0.05–0.5 mol%. The results showed that the optimal Tm 2 S 3 doping concentration was 0.38 mol% at which the glass exhibited an enhanced emission peaking at 1480 nm with a full width at half maximum (FWHM) over 100 nm.

Optical and DC-electric poling on AgX (X = Cl, I)-Doped chalcohalide glasses

The influence of the simultaneous polarized optical treatment (10-ns Nd:YAG lasers with a poser density of 3.6 GW/cm2) together with an electrostatic DC-electric field (up to 8 kV/cm) on GeS2-Ga2S3-AgX (X = Cl, I) and GeS2-Ga2S3-KBr chalcohalide glasses is explored. The maximal second-order susceptibility (SOS) was achieved for the AgI-doped specimen. In samples without silver halides, however, the SOS was below 0.25 pm/V. This fact may indicate the principal role of the high polarizability of Ag+ ions in the enhanced SOS. A common feature for all three glasses is that the SOS achieves maximal values after one minute of simultaneous DC-electrical optical treatment. Further treatment will not enhance the SOS values and can even lead to its decrease by several times. The independent measurement of the local temperature shows that local heating does not excess 5°–7°.

Near Infrared Broadband Emission from Bismuth–DysprosiumCodoped Chalcohalide Glasses

We investigate the broadband infrared emission of bismuth doped andbismuth/dysprosium codoped chalcohalide glasses. It is found that thebismuth/dysprosium codoping can drastically enhance the fluorescence ascompared with either bismuth or dysprosium doped glasses. Meanwhile,the full width at half maximum of bismuth/dysprosium codoped glasses isover 170 nm, which is the largest value among all the reportedrare-earth doped chalcohalide glasses. An ideal way for energyconsumption between bismuth and dysprosium ions is supposed. Suchimproved gain spectra of both bismuth and dysprosium ions may havepotential applications in developing broadband fibre amplifiers.

Third- and second-order optical nonlinearity of Ge–Ga–S–PbI 2 chalcohalide glasses

Two series of metal iodide doped chalcohalide glasses (100−2 x)GeS 2· xGa 2S 3· xPbI 2 (0⩽ x⩽20) and (100− x)(0.8GeS 2·0.2Ga 2S 3)· xPbI 2 (0⩽ x⩽15) were prepared and characterized. The microstructure of these glasses has been studied by Raman scattering spectra. Utilizing femtosecond time-resolved optical Kerr effect (OKE) technique at the wavelength of 820 nm, a largest third-order nonlinearity χ (3) of 2.07×10 −13 esu was obtained for the 90GeS 2·5Ga 2S 3·5PbI 2 glass, and it decreases with the addition of PbI 2 in both two series. After thermally poled, second-harmonic generation (SHG) has been observed in these glasses according to Maker fringe method and a large second-order nonlinearity χ (2) as well as 4 pm/V was obtained for the 70GeS 2·15Ga 2S 3·15PbI 2 glass. The variations of χ (2) and χ (3) on glass composition are ascribed to the evolution of micro-structural units in glass. These novel chalcohalide glasses would be expected to be the promising candidate materials for nonlinear optical devices.

Infrared-to-visible upconversion in Nd3+-doped chalcohalide glasses

The infrared to visible upconversion processes have been investigated for ${\mathrm{Nd}}^{3+}$-doped chalcohalide glasses with different halide modifiers by using steady-state and time-resolved laser spectroscopy. Two different upconversion mechanisms have been identified depending on the infrared excitation wavelength. When the excitation wavelength is resonant with the ${}^{4}{F}_{3/2}$ state, three main bands at 538, 600, and 675 nm are observed and attributed to emissions from the ${}^{4}{G}_{7/2}$ level. These upconverted emissions occur via energy-transfer upconversion involving two neodymium ions in the ${}^{4}{F}_{3/2}$ state. However, nonresonant excitation at higher energies than that of ${}^{4}{F}_{3/2}$ state (between states ${}^{4}{F}_{3/2}$ and ${}^{4}{F}_{5/2})$ or in resonance with the ${}^{4}{F}_{5/2}$ state, causes an additional blue emission to originate from the ${}^{2}{P}_{1/2}$ state. This latter upconverted emission can be attributed to excited-state absorption of the pump radiation. The proposed upconversion mechanisms responsible for the different emissions from levels ${}^{2}{P}_{1/2}$ and ${}^{4}{G}_{7/2}$ are supported by both the time evolution of the upconversion luminescence after infrared pulsed excitation and the upconversion luminescence excitation spectra.

Mid-infrared emissions and multiphonon relaxation in Dy 3+-doped chalcohalide glasses

Effects of Br addition into Ge 25Ga 10S 65 glasses on the mid-infrared emissions and multiphonon relaxation of Dy 3+ were investigated. Measured lifetimes of three energy levels emitting the infrared fluorescences increased with the addition of Br. Temperature-dependence of the multiphonon relaxation rates ( W mp=1/ τ m − 1/ τ R at low concentration of Dy 3+) showed the dominance of 5-phonon relaxation process at 375 cm −1 vibration associated with the asymmetric stretching of GeS 4 tetrahedra. A decrease in the multiphonon relaxation rates with Br addition is associated with an increase of the width of the 6F 11/2– 6H 9/2 manifolds of Dy 3+. It resulted in thermal depopulation of the lowest Stark component and thereby, decreased the multiphonon relaxation rates in Br-containing glasses.