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Fluorescence Studies of Dy3+ Ions in Silica Sol Gel
摘要： The fluorescence properties of Dy3+ ion are utilized to study the structural changes during the gel to glass transition of the silica xerogels. The fluorescence intensity ratio (yellow to blue, Y/B) is used as a measure of the symmetry of rare earth ion environment during the gel-glass conversion. The high value of the intensity ratio of gel heated to 1000 °C showed that the rare earth ions are embedded in the glassy silica network with an asymmetric environment. Fluorescence study is also used to characterize the effect of metal cation co-dopants on the state of aggregation of rare earth ions in silica sol gel. The addition of co-dopants inhibits the clustering of rare earth ions and promotes better dispersion. The inhibition of clustering is correlated with the generation of strong crystal field bonding sites for rare earth ions in the presence of co-dopants.
关键词： Rare earth doped materials,Luminescence,Sol gel
更新于2025-09-19 17:15:36
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Reliability of rare-earth-doped infrared luminescent nanothermometers
摘要： The use of infrared-emitting rare-earth-doped luminescent nanoparticles as nanothermometers has attracted great attention during the last few years. The scientific community has identified rare-earth-doped luminescent nanoparticles as one of the most sensitive and versatile systems for contactless local temperature sensing in a great variety of fields, but especially in nanomedicine. Researchers are nowadays focused on the design and development of multifunctional nanothermometers with new spectral operation ranges, outstanding brightness, and enhanced sensitivities. However, no attention has been paid to the assessment of the actual reliability of the measurements provided by rare-earth-doped luminescent nanothermometers. In fact, it is assumed that they are ideal temperature sensors. Nevertheless, this is far from being true. In this work we demonstrate that the emission spectra of rare-earth-doped nanothermometers can be affected by numerous environmental and experimental factors. These include the numerical aperture of the optical elements used for their optical excitation and luminescence collection, the local concentration of nanothermometers, optical length variations, self-absorption of the luminescence by the nanothermometers themselves, and solvent optical absorption. This work concludes that rare-earth-doped luminescent nanothermometers are not as reliable as thought and, consequently, special care has to be taken when extracting temperature estimations from the variation of their emission spectra.
关键词： reliability,solvent absorption,self-absorption,excitation power dependence,infrared luminescent nanothermometers,rare-earth-doped
更新于2025-09-19 17:15:36
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Fabrication of low loss channel waveguide in tungsten-tellurite glass by 11?MeV carbon ion microbeam for telecom C band
摘要： Channel waveguides were directly written in Er: TeO2W2O3 glass using 11 MeV C4+ ion microbeam with fluences in the range of 1·1014–5·1016 ion/cm2. The channel waveguides supported a single guided mode at λ = 1540 nm. Propagation losses of the as-irradiated channel waveguides were around 14 dB/cm. A 30-min thermal annealing at 150 °C in air reduced propagation losses at λ = 1400 nm to 1.5 dB/cm. This method produced channel waveguides with confinement and propagation losses comparable to or better than other current methods, such as MeV energy focused proton or helium ion beam writing.
关键词： Microstructure fabrication,Channel waveguides,Rare earth doped materials,Integrated optics,Optical design and fabrication
更新于2025-09-19 17:13:59
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CMOS-Compatible Optical Phased Array Powered by a Monolithically-Integrated Erbium Laser
摘要： An advanced CMOS-compatible 300-mm-wafer silicon-photonics platform is introduced that consists of a silicon layer with eight doping masks, two silicon-nitride layers, three metal and via layers, a dicing trench for smooth edge-coupled facets, and a gain-film trench that enables interaction between the gain material and waveguide layers. The platform was used to demonstrate an electrically-steerable integrated optical phased array powered by an on-chip erbium-doped laser. Lasing with a single-mode output, 30 dB side-mode-suppression ratio, and 40 mW lasing threshold was shown, and one-dimensional beam steering with a 0.85? × 0.20? full-width at half-maximum and 30?/W electrical steering efficiency was demonstrated. This system represents the first demonstration of a rare-earth-doped laser monolithically integrated with an active CMOS-compatible silicon-on-insulator photonics system.
关键词： Silicon photonics,rare-earth-doped lasers,integrated optical phased arrays,photonic integrated circuits
更新于2025-09-19 17:13:59
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High-performance upconversion luminescent waveguide using a rare-earth doped microtube with beveled ends
摘要： Upconversion luminescence-based waveguides can achieve optical signal transmission and visible light emission with near-infrared light excitation and their quality is highly dependent on the coupling efficiency between the light and waveguide. Here, a new luminescent waveguide formed by a rare-earth doped microtube with beveled ends was designed to increase the optical coupling efficiency for vertical waveguide-excitation. The beveled end enabled the near-infrared light to effectively couple into the waveguide and produce a visible transmission pattern and directional emission, which was not possible using conventional luminescent waveguides without beveled ends. It was found that the beveled end can not only improve the input and the output signal efficiency, but also control the coupling efficiency and transmission pattern. In particular, a coupling efficiency of B68% could be obtained with the optimized beveled waveguide with a rotation angle of 301. The high optical coupling efficiency and multi-channel luminescent waveguide enabled by the microtube with beveled ends allowed for a deeper understanding of vertical waveguide excitation, and it extends the potential applications of luminescent waveguides for bioimaging and optical communication.
关键词： rare-earth doped microtube,beveled ends,upconversion luminescence,waveguide,optical coupling efficiency
更新于2025-09-16 10:30:52
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Rare Earth Doped Optical Fibers with Multi-section Core
摘要： The gain bandwidth of a single-mode fiber is limited by the atomic transitions of one rare earth gain element. Here we overcome this long-standing challenge by designing a new single-mode fiber with multi-section core, where each section is doped with different gain element. We theoretically propose and experimentally demonstrate that this configuration provides a gain bandwidth well beyond the capability of conventional design, whereas the inclusion of multiple sections does not compromise single-mode operation or the quality of the transverse modal profile. This new fiber will be beneficial in realizing all fiber laser systems with few-cycle pulse duration or octave tunability.
关键词： Rare Earth Doped Optical Fibers,Gain Bandwidth,Fiber Laser Systems,Single-mode Fiber,Multi-section Core
更新于2025-09-12 10:27:22
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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 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 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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Tracing of dye molecules in living plants through NaGdF4:Yb3+,Er3+ fluorescent nanoprobes
摘要： In this paper, we demonstrated trace of dye molecules in living plants. The NaGdF4:Yb3+,Er3+ nanoparticles probe was used to detect the rhodamine B(RhB) in bean sprout. It is found that the fluorescencedye can be efficiently imbibed during the growing process and the absorbance presented a position dependence effect, which was supported by the upconversion spectra and the fluorescent image characterization. In addition, the concentration of the residual RhB in bean sprout can be efficiently traced by the synthesized probe based on the fluorescent resonant energy transfer. Finally, the relation between the excitation power, concentration and the ratio of yellow to green emission are discussed in detail. These results can be helpful in understanding the RhB dye molecules absorbance process in vegetable growth and provide an efficient way to trace the residual dyes in vivo plant.
关键词： Upconversion nanoprobes,Rare-earth-doped materials,fluorescence,Biological sensing and sensors,luminescence
更新于2025-09-10 09:29:36