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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Rare-Earth Doped Phosphate Optical Fibres and Rods for Compact Pulsed Optical Amplification
摘要： In the last decade high energy and high peak power pulsed laser sources have been in a great demand for a variety of applications such as remote sensing (LIDAR, DIAL), range findings, communications systems and material processing. Since the energy of the pulsed laser oscillator is generally much lower than the one required for the applications, a fibre amplifier is commonly used to boost the output power, realizing the so called MOPA (Master Oscillator Power Amplifier) laser architecture. The realization of a fibre amplifier requires an active medium with high optical gain in short length, in order to mitigate nonlinear optical effects. Multicomponent phosphate glasses are recognized to be an ideal host material for the realization of these fibres, as they can be doped with large amounts of rare earth (RE) ions (up to 1021 ions/cm3) without clustering, thus allowing the fabrication of extremely compact active devices with high optical gain (> 5 dB/cm) in short length [1,2]. Moreover, phosphate glasses possess good thermo-mechanical properties, high emission cross-sections, high optical damage threshold and are less susceptible than silica to photodarkening [3,4]. With the aim of realizing short-length amplifiers in the 1 μm and 1.5 μm wavelength range, highly Yb3+ and Yb3+-Er3+-doped custom phosphate glass compositions were designed and fabricated by melt-quenching technique. Suitable cladding compositions were explored. The manufactured glasses were thoroughly investigated. First of all, they were thermo-mechanically characterized, then the glasses underwent optical characterization such as refractive index measurement, FTIR spectroscopy and, for active glass, RE emission spectroscopy resolved in time and frequency. Phosphate fibers and rods were then manufactured by preform drawing using a custom induction heated optical fiber drawing tower, with the preform being obtained by rod-in-tube technique. Preliminary results of optical amplification are presented for a single stage MOPA, both in the 1 μm and 1.5 μm wavelength range.
关键词： compact pulsed optical amplification,Yb3+-Er3+-doped,MOPA,phosphate glass compositions,Yb3+,rare-earth doped phosphate optical fibres
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - UV Luminescence in Ho:ZBLAN Glasses
摘要： Compact, short-wavelength lasers are continuously considered as one of the most attractive among all coherent light sources. A very wide range of applications such as data storage, photolithography, medical diagnostics and sterilization motivates research and development on new active materials which can efficiently emit light in the UV spectral range. There are three general methods to achieve UV and visible light emission. The first are semiconductor-based LEDs and laser diodes - in the recent years a rapid progress in the field of semiconductor lasers has been observed resulting in a variety of commercially available short-wavelength laser diodes. These impressive devices, however, are not free from some disadvantages, like poor quality of the beam and limited output power. That’s why other sources continue to attract researchers’ attention. The second method deploys nonlinear crystals, which enable obtaining short wavelength emission by the frequency multiplication. The third way to achieve UV and visible light is to directly use the optical transitions within rare earth ions in solid state media [1-2]. This work is focused on this last method.
关键词： short-wavelength emission,Ho:ZBLAN glasses,optical spectroscopy,rare earth ions,UV luminescence
更新于2025-09-11 14:15:04
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Structural, Spectroscopic, and Excitonic Dynamic Characterization in Atomically Thin Yb <sup>3+</sup> ‐Doped MoS <sub/>2</sub> , Fabricated by Femtosecond Pulsed Laser Deposition
摘要： The large area deposition and synthesis of 10 mm × 10 mm atomically thin Yb3+-doped MoS2 films by femtosecond pulsed laser deposition on a silica glass optical platform for device applications are demonstrated for the first time. The presence of Yb3+-ion doping is confirmed using photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The Yb3+-doped MoS2 films, when excited with a 976 nm laser, exhibit room temperature PL with a peak at 1002 nm. The XPS and Raman spectroscopic analyses of the Yb3+-doped and undoped films show that the deposited films are a mixture of 2H- and 1T-MoS2 after postdeposition annealing at 500 °C. The density functional theory analysis shows that the 1T phase is metastable by +77 kJ (≈0.8 eV) mol-1, when compared with the 2H state at 0 K. Ultrafast transient nonlinear optical spectroscopic measurements prove that the saturable absorption of undoped MoS2 is significantly modified after Yb3+-ion doping, by displaying dopant-host structure charge transfer. The complex transient absorption line shape shows a combination of bleach (negative) signals at the A (670 nm) and B (630 nm) exciton energies, and a strong induced absorption below the A exciton level. The results presented herein provide critical insight in designing novel rare-earth-ion doped 2D materials and devices.
关键词： molybdenum disulfide,femtosecond pulsed laser deposition,saturable absorber,rare-earth ion photoluminescence,nonlinear optical properties
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Rare-Earth Doped Oxide Glasses and Fibers for Lasers Emitting in the 2÷3 μm Spectral Range
摘要： The aim of this investigation is the search of novel promising materials for solid-state and fiber lasers emitting in the spectral range 2÷3 microns, i.e. out of the range where the well-developed rare-earth doped silica fibers can successfully operate. We have stopped our choice on tellurite and calcium aluminate glasses. In contrast to silica glasses, both these glass types can contain high (>1021 cm-3) amounts of rare earth dopants. In contrast to ZBLAN glass that is widely used for mid-infrared fiber lasers, both tellurite and aluminate glasses can be quite stable to air moisture. Furthermore, calcium aluminate glasses are prominent for their extraordinary mechanical properties (better than those of fused silica). Our spectral investigations have shown that deeply dehydrated tellurite glasses (TG) are very suitable hosts for 2.3 μm Tm3+ lasers and can be also used as a host for 2.7 μm Er3+ lasers. As for calcium aluminate glasses (CAG), their phonon spectrum is not suitable for 2.7 for μm lasers. But the emission properties of Tm3+ ions in this host show some unusual feature. Two-micron Tm3+ emission band in CAG is anomalously widened and red shifted so that it overlaps well with the 2.3μm emission band. Thus continuous tuning of Tm doped CAG fiber laser from ~2μm up to ~2.4μm is conceivable. Figures 1 and 2 give some examples of bulk Tm-doped TG and CAG lasing properties. Fig. 1 shows the 2.3μm lasing parameters of 30 mm long TG sample when pumped by a pulsed ruby laser. CAG in similar conditions showed cascade lasing at 2.3μm and 2.1μm. Fig. 2 shows the lasing parameters of a quasi CW diode-pumped CAG chip laser, operating at the wavelength of 2.1 μm. Surely most practical applications of such laser glasses require fiber configuration. We have developed the laboratory technology of TG multimode and single-mode double-cladding fibers fabrication. In Tm doped TG fibers laser action at 1.9 μm and 2.3 μm was successfully demonstrated. Er doped fibers were also manufactured but 2.7 μm laser action in them requires highly reflective fiber Bragg gratings to be made in them. Fabrication of CAG fibers is a very complicated technological task due to high tendency of CAG to devitrification. Nevertheless, using “rod-in-tube” method we have prepared an optical fiber starting from Tm-doped CAG rod in a silica tube. Unfortunately, the core of this fiber contained too much SiO2 diffused from the cladding. The choice of a suitable lower-melting cladding glass should solve the problem. Thus, the properties of deeply dehydrated rare-earth doped tellurite and calcium-aluminate glasses are shown to be quite pertinent for lasers emitting in the 2÷3 μm spectral range.
关键词： rare-earth doped oxide glasses,mid-infrared spectral range,fiber lasers,tellurite glasses,calcium aluminate glasses
更新于2025-09-11 14:15:04
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Prediction of Thermal Coupled Thermometric Performance of Er <sup>3+</sup>
摘要： Predicting thermometric performance for diverse materials will facilitate the selection and design of nanothermometers to meet complex environment and specific signal output with saving a lot of time and expense. Herein we explore and unveil the thermal coupled thermometric performance of Er3+/Yb3+ co-doped a set of host lattices via the chemical bond theory of complex crystals. The unknown B and ΔE values of the thermometry are accurately estimated by the chemical bond parameters, further deepening our cognition of the correlation between luminescence properties of Er3+ ions and microscopic crystal structure. This allows us to precisely forecast the thermal coupled thermometric performance of Er3+ for varying host lattices in advance.
关键词： nanothermometers,chemical bond theory of complex crystals,thermally coupled levels,rare earth,luminescence intensity ratio thermometry
更新于2025-09-11 14:15:04
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Ordered langasites La3Ga5MO14:Eu3+ (M = Zr, Hf, Sn) as red-emitting LED phosphors
摘要： The temperature-dependent luminescence behavior of three ordered langasites La3Ga5ZrO14 (LGZr), La3Ga5HfO14 (LGHf) and La3Ga5SnO14 (LGSn) doped with up to 20% Eu3+ were investigated. Band gap energies of 4.32 eV (LGZr), 4.43 eV (LGHf), and 4.46 eV (LGSn) were determined by diffuse reflection measurements of the undoped compounds. The influence of the structural differences on the luminescence properties of the three langasites were investigated by means of excitation, emission (77-500 K) and luminescence lifetime measurements (77-300 K). The quenching temperatures of the three langasites do vary. They were attained using different excitation wavelengths in the charge transfer band (300 nm) and in the 4f levels (394 nm). LGSn:Eu 20% Eu3+ showed the best temperature performance with intensities at 500 K of 85% (300 nm) and 67% of the intensity measured at 77 K. At room temperature and with an excitation wavelength of 394 nm, maximum quantum efficiencies of 41% for LGZr:Eu 20% Eu3+, 58% for LGHf:Eu 20% Eu3+ and 68% for LGSn:Eu 20% Eu3+ were reached. The quenching behavior observed is explained by semi-quantitative configurational coordinate diagrams. Based on these results and the high red color purity, the langasites were built into LEDs with (In,Ga)N chips emitting at 394 nm, to test the applicability of the materials as red LED phosphors.
关键词： inorganic materials,optical properties,rare earth alloys and compounds,phosphors,oxide materials,luminescence
更新于2025-09-11 14:15:04
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Structural and luminescence properties of Dy3+-doped alkali fluoroborophosphate glasses for white LEDs applications
摘要： A new series of Dy3+-doped alkali fluoroborophosphate glasses were prepared by conventional melt quenching technique, and their structural and optical properties were investigated through XRD, FTIR, optical absorption, luminescence and decay measurements. The X-ray diffraction pattern reveals the amorphous nature of the prepared glasses. The fundamental stretching vibrations of various borate (BO3 and BO4) and phosphate (PO4) networks were identified through the FTIR analysis. The nature of the metal–ligand bonding and the electronic band structure has been investigated using the absorption spectra. The Judd–Ofelt (JO) intensity parameters (X2, X4 and X6) were evaluated, and the experimental oscillator strength values were also calculated. Using the JO intensity parameters, radiative properties like radiative transition probability (A), stimulated emission cross section (rE) and branching ratios (bR) for the emission transitions of the Dy3+ ions have been calculated. The luminescence spectra exhibit two visible bands of 4F9/2 → 6H15/2 (Blue) and 4F9/2 → 6H13/2 (Yellow). The decay time of the 4F9/2 level has been measured from the decay profiles and compared with the calculated lifetimes. The yellow-to-blue (Y/B) ratios and color coordinates have been calculated from the luminescence spectra and can be considered for white light emitting diodes applications.
关键词： Absorption,CIE diagram,Melt quenching technique,Rare-earth,Photoluminescence
更新于2025-09-11 14:15:04
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[IEEE 2019 21st International Conference on Transparent Optical Networks (ICTON) - Angers, France (2019.7.9-2019.7.13)] 2019 21st International Conference on Transparent Optical Networks (ICTON) - Enhanced Pump Absorption Efficiency in Coiled and Twisted Double-Clad Fibers for Fiber Lasers
摘要： High-power operation of fiber lasers was mainly enabled by the invention of cladding-pumping in a double-clad fiber structure. Pump absorption is enhanced by broken circular symmetry of inner cladding cross-sections and by mode-scrambling of the pump modes resulting from unconventional fiber coiling. However, theoretical studies were limited to the assumption of a straight fiber until recently, when the rigorous model accounting for double-clad fiber bending and twisting was described. It was found that squeezing of the effective area of the pump radiation due to fiber bending plays an important role in cladding-pump absorption enhancement. We review results of numerical modeling of pump absorption in various types of double-clad fibers, e.g., with cross-section shape of hexagon, stadium, and circle; two-fiber bundle (so-called GTWave fiber structure) a panda fibers are also analyzed. The presented results can have a practical application and potential impact in the construction of fiber lasers: with pump absorption efficiency optimized by our new model (the other models did not take into account fiber twist), the double-clad fiber of shorter length can be used in the fiber lasers and amplifiers. This dramatically minimizes the deleterious effect of background losses and nonlinear effects.
关键词： fiber lasers,thulium-doped fibers,rare-earth-doped fibers,optical pumping
更新于2025-09-11 14:15:04
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[IEEE 2019 Photonics North (PN) - Quebec City, QC, Canada (2019.5.21-2019.5.23)] 2019 Photonics North (PN) - Design of a mid-infrared multispecies gas sensor based on Pr <sup>3+</sup> -doped chalcogenides waveguides
摘要： Praseodymium-doped selenide thin films are deposited by radio frequency (RF) magnetron sputtering on thermally oxidized silicon wafers. Ridge waveguides are then processed using photolithography and dry etching techniques. Under optical pumping at 1.55 μm, broadband guided mid-infrared photoluminescence is recorded between 3.5 and 5.5 μm. Optical design confirmed that these active waveguides allow single-mode optical propagation at different absorption wavelengths of important environmental gases (CO2, CO, NO). Mid-Wave Infrared (MWIR) multimode interferometer (MMI)-based demultiplexer are designed for multispecies gas sensing.
关键词： MWIR,MMI,mid-infrared,multispecies sensing,rare-earth,chalcogenides
更新于2025-09-11 14:15:04
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Influence of back gate voltage on electrical transport in Zn <sub/>1-(y+x)</sub> (Al <sub/>x</sub> ,Eu <sub/>y</sub> )O thin films
摘要： We investigated the back gate voltage (VBG) dependent electrical conductivity of Zn1-(y+x)(Alx,Euy)O (x = 0.00, 0.01; y = 0.00, 0.01, 0.02 and 0.05) thin films. Zn1-(y+x)(Alx,Euy)O (x = 0.00, 0.01; y = 0.00, 0.01, 0.02 and 0.05) thin films were synthesized with combining sol-gel and spin coating techniques. Electrical conductivity measurements was monitored by longitudinal conductivity curves of Eu doped (Zn, Al)O thin films. The measurements show a sharp decrease or increase in conductivity of Eu doped (Zn, Al)O thin films by an applied ±VBG, which was not observed for Al doped ZnO thin films. The Eu amount in (Zn, Al)O lattice was the key parameter to manage the change in conductivity by ±VBG. The highest increase in conductivity by applied ±VBG was observed for 1 mol% Eu-doped Zn1-(y+0.01)(Al0.01,Euy)O films, which also performed the highest longitudinal conductivity without a VBG. By applied VBG = ?100 V, the change ratio in conductivity reached up to 436% for 1 mol% Eu doped (Zn, Al)O thin films. The response to VBG were drastically decreased by increase in Eu amounts in the lattice, and furthermore no change in conductivity was observed for 5 mol% Eu doped (Zn, Al)O thin films.
关键词： dopant,oxide semiconductors,II–VI semiconductors,rare earth element,back gate voltage
更新于2025-09-11 14:15:04