1,720,988 research outputs found
2.9 µm lasing from a Ho<sup>3+</sup>/Pr<sup>3+</sup> co-doped AlF<sub>3</sub>-based glass fiber pumped by a 1150 nm laser
No full textHo3+/Pr3+ co-doped AlF3-based glass fibers were fabricated by using a rod-in-tube method based on the matrix glass composition of AlF3-BaF2-CaF2-YF3-SrF2-MgF2-LiF-ZrF4-PbF2. Under the pump of a 1150 mW Raman fiber laser, a 2.9 µm laser was observed in a 19 cm long Ho3+/Pr3+ co-doped AlF3-based glass fiber with an output power of 173 mW and a slope efficiency of 10.4%. Ho3+/Pr3+ co-doped AlF3-based glasses were fabricated to investigate the deactivation effects of Pr3+ ions on the Ho3+:5I7 level. Our results showed that the Ho3+/Pr3+ co-doped AlF3-based glass fibers are potential gain media for ~2.9µm lasers
2.4 μm fluorescence of holmium doped fluoroaluminate glasses
No full textHo3+-doped fluoroaluminate glass samples were fabricated by melt-quenching. Intense 2.4 μm emission was observed under pumping of a 638 nm laser diode, which was ascribed to the Ho3+:5F5→5I5 transitions. The Judd-Ofelt (J-O) theory was applied to predict the radiative probabilities, radiative lifetimes, and branch ratios of Ho3+ transitions. The emission and absorption cross-sections were calculated, and the gain coefficients determined for a 1 mol% Ho3+ concentration. Our results indicate that Ho3+-doped fluoroaluminate glass has a potential for developing fiber lasers operating at 2.4 μm
Broadband 2.7 µm mid-infrared emissions in Er3+-doped PbO–PbF2–Bi2O3–Ga2O3 glasses
No full textBroadband emission at 2.7 µm is observed in an Er3+-doped PbO−PbF2−Bi2O3−Ga2O3 glass. The measured emission band full-width-at-half-maximum (FWHM) is ∼184.4 nm, approximately 36 nm wider than that of fluoride glasses. The 2.7 µm emission intensity is almost twice as strong as that of fluoride glasses. The peak values of emission and absorption cross-sections are calculated to be 1.54 × 10−20 cm2 and 1.19 × 10−20 cm2, respectively. This oxyfluoride heavy metal glass shows potential as broadband mid-infrared emission gain material
Effect of Tm<sup>3+</sup> concentration on the emission wavelength shift in Tm<sup>3+</sup>-doped silica microsphere lasers
No full textIn this work, a Tm3-doped solgel silica microsphere lasing at 2.0 μm is reported. Microspheres with different Tm3 concentrations are fabricated by overlaying different Tm3 concentration solgel solutions on the surface of a pure silica microsphere resonator and then annealing the sample with a CO2 laser. Based on a traditional fiber taper–microsphere coupling method, single and multimode microsphere lasing in the wavelength range 1.8–2.0 μm is observed if an 808 nm laser diode is used as a pump source. A relatively low threshold pumping power of 1.2 mW is achieved using this arrangement. This solgel method allows for an easy varying of the Tm3 doping concentration. The observed laser output shifts to longer wavelengths when the Tm3 doping concentration increases. This has been explained by the larger Tm absorption at shorter wavelengths. The ability to fabricate solgel co-doped silica glass microlasers represents a new generation of low threshold and compact infrared laser sources for use as miniaturized photonic components for a wide range of applications, including gas sensing and medical surgery.</p
Infrared-laser and upconversion luminescence in Ho<sup>3+</sup>-Yb<sup>3+</sup> codoped tellurite glass microsphere
No full textIn this letter, Ho3+-Yb3+ codoped tellurite glasses were fabricated using the melting-quenching method to produce optical microsphere cavities. A 980 nm excitation laser was coupled into the microsphere through a fiber taper, providing lasing at around 2.0 μm and upconversion luminescence in the visible (380-780 nm)
Ultra-broadband near-infrared photoluminescence in Er<sup>3+</sup>-Ni<sup>2+</sup>co-doped transparent glass ceramics containing nano-perovskite KZnF<sub>3</sub>
No full textIn this article, ultra-broadband photoluminescence in near-infrared is achieved in KZnF3 glass ceramics doped with Er3+and Ni2+ ions. Er3+-Ni2+ co-doped fluorosilicate glass and glass ceramics embedded with perovskite nanocrystals were fabricated and efficient energy transfer (ET) from Er3+ to Ni2+ ions was confirmed by luminescence spectra and decay curves. In the glass ceramic samples, Ni2+ ions were effectively sensitized by Er3+, and ultra-broadband photoluminescence from 1400 to 2300 nm was observed when a 980 nm laser was used as a pump, as shown in Fig. 1. The temperature and humidity stability of the glass ceramic samples was characterized from the measured transmittance. These results demonstrated that Ni2+-Er3+ co-doped glass ceramics have significant potential for application in optical communication and broadband amplifiers
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
3.9 µm emission in Nd<sup>3+</sup> sensitized Ho<sup>3+</sup> doped fluoroaluminate glasses
No full textHo3+ and Nd3+/Ho3+ doped fluoroaluminate glass samples were fabricated by the melt-quenching method and showed high transmittance and a wide transparency window. Under 808 nm pumping, emission at 3.9 µm, corresponding to the Ho: 5I5→5I6 transition, was observed. The presence of Nd3+ strongly enhances the Ho3+ emission. The emission and absorption cross-sections were calculated using the Judd-Ofelt, Füchtbauer-Ladenburg and McCumber theories and the energy transfer mechanism between Nd3+ and Ho3+ was analyzed. The most efficient 3.9 µm emission was obtained when the concentration ratio of Nd3+: Ho3+ is 1:2
Enhancement mechanisms of Tm<sup>3+</sup>-codoping on 2 µm emission in Ho<sup>3+</sup> doped fluoroindate glasses under 888 nm laser excitation
No full textHo3+ doped and Ho3+/Tm3+ co-doped fluoroindate glass samples were prepared and their emission properties were compared. Under 888 nm laser excitation, the emission at 2µm of Ho3+ ions with co-doping 2 mol% Tm3+ ions had a 2.9-fold improvement compared with that of Ho3+ doped. The absorption and emission spectra, and energy level lifetime of Ho3+/Tm3+ co-doped glass samples were measured to analyze the energy transfer processes and enhancement mechanisms. The luminescence intensity at 2µm can be greatly increased due to the bidirectional energy transfer between Tm3+ and Ho3+ ions
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