Dongbing He

Tunable white light emission from γ-irradiated Ag/Eu co-doped phosphate glass phosphor

We report a new tunable white light emission from γ-irradiated Ag/Eu co-doped phosphate glass phosphor. The appearance of Eu2+ and silver aggregates after γ-irradiation was confirmed via Electron paramagnetic resonance (EPR), absorption, and emission spectra. The effects of Ag/Eu doping concentration and excitation wavelengths on white light emission were discussed. A pure white light emission with the chromaticity coordinates (X = 0.331, Y = 0.329) was generated using the optimal sample under excitation at 360 nm.

Phosphate single mode large mode area all-solid photonic crystal fiber with multi-watt output power

An index-depressed active core, single-mode phosphate all-solid large-mode-area photonic crystal fiber (PCF) is theoretically investigated using full-vectorial finite difference approach and experimentally realized. The PCF has a maximum output power of 5.4 W and 31% slope efficiency. Single-mode operation is realized through PCFs with core diameters of 30, 35, and 40 μm, respectively. The beam quality is not degraded even at maximum output power. Our simulations and experiments reveal that the laser performance is significantly affected by the center-to-center distance between the two nearest rods Λ, the rod diameter d, and their ratio d/Λ, implying that much attention should be given in employing optimal parameters to achieve excellent laser performance.

Phosphate ytterbium-doped single-mode all-solid photonic crystal fiber with output power of 13.8 W

Single-mode ytterbium-doped phosphate all-solid photonic crystal fiber (AS-PCF) with 13.8 W output power and 32% slope efficiency was reported. By altering the diameter of the rods around the doped core and thus breaking the symmetry of the fiber, a polarization-maintaining AS-PCF with degree of polarization of >85% was also achieved, for the first time to knowledge, in a phosphate PCF.

Yb/Er co-doped phosphate all-solid single-mode photonic crystal fiber

An all-solid Yb3+/Er3+ co-doped single-mode phosphate photonic crystal fiber (PCF) with Watt-level output power and 20 μm core diameter is demonstrated for the first time. A PCF whose refractivity of the active core is lower than that of the background glass is suggested and theoretically confirmed to be in single-mode operation at 40 μm core diameter.

Seven-core neodymium-doped phosphate all-solid photonic crystal fibers

We demonstrate a single-mode seven-core Nd-doped phosphate photonic crystal fiber with all-solid structure with an effective mode field diameter of 108 μm. The multicore fiber is first theoretically investigated through the finite-difference time-domain method. Then the in-phase mode is selected experimentally by a far-field mode-filtering method. The obtained in-phase mode has 7 mrad mode field divergences, which approximately agrees with the predicted 5.6 mrad in seven-core fiber. Output power of 15.5 W was extracted from a 25 cm fiber with slope efficiency of 57%.

Optical and thermal properties of a new Nd-doped phosphate laser glass

In this paper, we report the optical and thermal properties of a new Nd-doped phosphate laser glass. Glass samples with 0.5-3.7 wt% Nd-doping concentrations were prepared, annealed, cut and polished for different measurements, including glass density and refractive index, absorption spectra and emission cross section, as well as laser properties. A Mach- Zehnder interferometer was used to measure the temperature coefficient of refractive index (dn/dT) and optical path length (dS/dT) in the temperature range of 30-100 °C. Moreover, by increasing the glass temperature up to 500 °C, the thermal expansion of this new glass was also measured. On the basis of these optical, thermal and thermo-optic parameters, we calculated and analyzed some of glass parameters, such as the electronic polarizability of oxygen ions, the optical basicity of this phosphate-based glass, and especially discussed their thermal shock resistance properties. It is suggested that this new Nd-doped phosphate laser glass is an excellent candidate for high energy and high repetition rate laser applications.

Compact Single-Mode Nd-Doped Silicate Glass Multitrench Fiber With 40 μm Core Diameter

We report a 40 μm core-diameter single-mode multitrench fiber (MTF) based on Nd-doped silicate glass. Both the delocalization effect and leaky nature were considered in the design of the MTF. The silicate MTF was designed and fabricated using the rod-in-tube method. A maximum laser output power of ∼8.4 W with a slope efficiency of 54% was obtained from a 10-cm-long single-mode MTF.

Very Large-Mode-Area, Symmetry-Reduced, Neodymium-Doped Silicate Glass All-Solid Large-Pitch Fiber

This paper reports, for the first time to our knowledge, a very large-mode-area, Nd-doped silicate glass all-solid large-pitch fiber (AS-LPF) with a core diameter of up to 75 μm. The concepts of the delocalization effect and differential loss were considered simultaneously to evaluate the single-mode operation of the AS-LPF. By reducing the symmetry of the fiber, the single-mode operation of the 75-μm AS-LPF was theoretically predicted using the finite-difference time-domain method and was experimentally fabricated. An output power of ~9.3 W with a slope efficiency of 41% was obtained for a 60-cm-long fiber.

Ytterbium-doped phosphate glass single mode photonic crystal fiber with all solid structure

A single-mode 15µm core diameter ytterbium-doped phosphate photonic crystal fiber (PCF) with all solid (AS) structure was reported. 8.2 W output power with 29% slope efficiency was extracted from the AS-PCF with length of 45 cm.

Enhancement of up-conversion luminescence properties in Yb 3+ /Tm 3+ /Er 3+ tri-doped transparent oxyfluoride tellurite glass ceramics

Optically transparent Er3+/Tm3+/Yb3+ tri-doped oxyfluoride tellurite based nano-crystallized glass ceramics with the batching composition of 73TeO2-15ZnO-7ZnF2-3YF3-1.5YbF3-0.3ErF3-0.2TmF3 (mol%) is prepared by a conventional melting quenching and the subsequent heat treatment processes. The sizes of grown nano-crystals in glass matrix appear to be smaller than 100 nm from the scanning electron microscope measurement. Visible up-conversion luminescence of the as melted glass and glass ceramics is investigated. The three-color up-conversion luminescence intensities by 980-nm pumping are increased significantly due to the heat treatment, and the blue intensity increases with a higher magnitude than other wavelengths after heat treatment.