Feifei Huang

Ho 3+ /Yb 3+ codoped silicate glasses for 2 μm emission performances

This paper discuss a series of Ho³⁺/Yb³⁺ codoped silicate glasses prepared by the melting method. 2 μm emissions of the samples are observed under the pump of 980 nm LD. The Judd-Ofelt parameters (Ω(λ)) and radiative properties are calculated and analyzed; the spontaneous transition probability can reach 78.71  s⁻¹. From the fluorescence spectra, the peak absorption and emission cross section of Ho³⁺ are 2.36×10⁻²¹ and 5.05×10⁻²¹ cm², respectively. In addition, we analyze the energy transfer process of Yb³⁺:  ²F(5/2) level to Ho³⁺:  ⁵I₆ level. Considering the luminance properties and good thermal property, we indicate that Ho³⁺/Yb³⁺ codoped silicate glass is a potential laser glass for the efficient 2 μm laser.

Spectroscopy of thulium and holmium co-doped silicate glasses

In this study, the spectroscopic properties of Tm3+/Ho3+ co-doped silicate glasses under an 808 nm diode laser excitation are reported to discover their potential laser performance. To confirm the best candidates for glass fiber drawing, the optimal ratio of Tm3+ and Ho3+ is 1: 0.3. We calculate and discuss the J-O parameters (Ωt), the transition probability (A) of the transition from 5I7 to 5I8 is 129.89s−1 and the calculated lifetime (τrad) is 7.70 ms, respectively. The maximum emission cross section of the transition from Ho: 5I7→5I8 is 7.59 × 10−21 cm2 at 2065 nm as well as the gain coefficient of the STH glasses is discussed. The energy transfer between Tm3+ and Ho3+ plays an important role in the luminescence process. The sample doped with 1 mol% Tm2O3 and 0.3 mol% Ho2O3 presents a broad band spectrum with a full width at half-maximum of 189 nm, the transfer efficiency from Tm3+ to Ho3+ is 0.6702. Energy transfer constant is 63.2 × 10−40 cm6 /s and the measured fluorescence lifetimes of the sample is 0.637 ms, and the ΔT is 167 °C.These values indicate that the Tm3+/Ho3+ co-doped silicate is a promising way to achieve 2 μm laser emissions.

Ho³⁺/Er³⁺ co-doped fluoride glass sensitized by Tm³⁺ pumped by a 1550 nm laser diode for efficient 2.0 μm laser applications.

In the present Letter, a high-emission intensity of 2.0 μm is reported for Ho(3+)/Er(3+) co-doped fluoride glass sensitized by Tm(3+) ions under 1550 nm excitation. The measured absorption spectra do not show clustering in the local ligand field, which also demonstrates that Er(3+) ions are efficiently excited by pumping and energy transfer (ET) to Ho(3+) and Tm(3+) ions. The enhanced Ho(3+):2.0  μm emission has a maximum emission cross section (4.8×10(-21)  cm(2)). An ET mechanism based on the enhanced 2.0 μm emission and other reduced near-infrared emissions is discussed. Results show that the addition of Tm(3+) ions populates the Ho(3+):(5)I(7) level through the channel at the Tm(3+):(3)F(4) level between Er(3+) and Ho(3+) ions. The spectroscopic characteristics and thermal property of Er(3+)/Ho(3+)/Tm(3+) tri-doped ZBYA glass reveal that the material is an attractive host for 2.0 μm lasers.

Tm 3+ -doped lead silicate glass sensitized by Er 3+ for efficient ~2 μm mid-infrared laser material

Er3+/Tm3+ co-doped lead silicate glasses with low phonon (953cm-1) and good thermal stability were synthesized. The ~2μm mid-infrared emission resulting from the 3F4→3H6 transition of Tm3+ sensitized by Er3+ has been observed by 808nm LD pumping. The optimal luminescence intensity was obtained in the sample with 1Tm2O3/2.5Er2O3 co-doped. Moreover, the energy transfer mechanism from Er3+ to Tm3+ ion was analyzed. Absorption and emission cross section have been calculated. The calculated maximum emission cross section of Tm3+ is 2.689×10-21cm2 at 1863nm. Microparameters of energy transfer between Er3+ and Tm3+ ions have also been analyzed. These results ensure that the prepared Er3+/Tm3+ co-doped lead silicate glasses have excellent spectroscopic properties in mid-infrared region and provide a beneficial guide for mid-infrared laser material.

Intense 2.7 μm emission in Er3 + doped zinc fluoride glass

A novel erbium ion doped zinc fluoride glass was prepared. 2.7μm emission and transmittance properties together with thermal ability were investigated. An enhanced 2.7μm emission was observed by introducing ZnF2 in the ZrF4-based fluoride glass. Meanwhile, the J-O parameters and branching ratios (β) of Er3+-doped zinc fluoride glass were calculated and analyzed. The present Er3+-doped zinc fluoride glass with large emission cross-section (0.92×10-20cm2) and long decay lifetime (2.05ms) at 2.7μm indicates that it have very promising applications for solid state lasers around 3μm.

Investigation of broadband mid-infrared emission and quantitative analysis of Dy-Er energy transfer in tellurite glasses under different excitations

Broadband mid-infrared emissions are obtained from Dy3+/Er3+ co-doped tellurite glasses under 808 or 980 nm excitation. The maximum effective emission bandwidths of mid-infrared emission is 92.45 nm in Dy3+/Er3+ co-doped tellurite glass pumped by 808 nm, while it can reach 209.00 nm pumped by 980 nm. The effects of different laser excitations on the energy transfer mechanism between Dy3+ and Er3+ ions have been investigated in tellurite glasses. Under 808 nm excitation, the energy transfer efficiency from Er3+:4I13/2 to Dy3+:6H11/2 level is 73.1% and the energy transfer coefficient from Er3+:4I11/2 to Dy3+:6H5/2 level and from Er3+:4I13/2 to Dy3+:6H11/2 level are 6.89 × 10−38 and 0.01 × 10−38 cm6/s, respectively. Under 980 nm excitation, the energy transfer efficiency from Er3+:4I13/2 to Dy3+:6H11/2 level can reach as high as 80%. Moreover, the maximum emission cross-section of 2500-3100 nm broadband emission when pumped by 808 nm is 1.90 × 1020 cm2 at 2765 nm, while it can reach as high as 4.99 × 1020 cm2 at 2724 nm pumped by 980 nm. Thus, the 980 nm excitation is more efficient for Dy3+/Er3+ co-doped tellurite glass to realize low-threshold and high gain applications at broadband mid-infrared laser.

Positive influence of Ce 3+ on effective transfer Yb 3+ : 2 F 5/2 → Ho 3+ : 5 I 6 in silica-germanate glass for mid-infrared applications

A1.5 time enhancement of a 2.0 μm emission was achieved successfully in Yb3+/Ho3+ doped silica-germanate glass with a 0.1 mol% Ce3+ addition, which possesses a larger emission cross section (4.43 × 10−21 cm2). According to the measured absorption spectra, the Judd-Ofelt parameters and radiative properties were calculated and discussed. The energy transfer mechanisms existed in Ho3+, Yb3+ and Ce3+ ions were investigated based on absorption, upconversion and fluorescence spectra. Meanwhile, the decay profiles of several levels were measured to further examine the enhanced mid-infrared emissions. Moreover, a high energy transfer microscopic parameter (7.54 × 10−40cm6/s) of Yb3+→Ho3+ process was obtained when 0.1 mol% Ce3+ ions were introduced into the Ho3+/Yb3+ system. All results indicate that the Yb3+/Ho3+/Ce3+ tri-doped silica-germanate glass is a promising candidate material for improving the Ho3+ 2.0 μm fiber laser performance.

Influence of excitation power and doping concentration on the upconversion emission and optical temperature sensing behavior of Er 3+ : BaGd 2 (MoO 4 ) 4 phosphors

Generally, the effects of excitation power and dopant concentration on the optical temperature sensing behaviors of rare earth (RE) doped materials based on the fluorescence intensity ratio (FIR) technique are disregarded. In this paper, Er3+: BaGd2(MoO4)4 phosphors with different concentrations were fabricated by the high temperature solid-state reaction method. The results show that the variation of FIR (2H11/2/4S3/2) with excitation power is not only related to the laser-induced heating effect, but also the diverse power-dependences of 2H11/2 and 4S3/2 levels. Consequently, the temperature calibration curves change at different excitation power densities. When the calibration curve obtained at a low power density is applied to estimate the temperature of the object excited at a high power density, a large overestimate of the temperature rise induced by the optical heating effect can be caused. Besides, the temperature sensing sensitivity depends on the Er3+ doping concentration, which increases first with concentration to a maximum and then reduces. The maximal absolute sensitivity is ~110.5 × 10−4 K−1 in 5mol% Er3+: BaGd2(MoO4)4 phosphor, which is among the highest values of RE ions doped phosphors based on thermally coupled levels recorded before.

2.8 μm emission and OH quenching analysis in Ho 3+ doped fluorotellurite-germanate glasses sensitized by Yb 3+ and Er 3+

The use of Yb3+ and Er3+ co-doping with Ho3+ to enhance and broaden the Ho3+: 5I6 → 5I7 ~2.8 μm emissions are investigated in the fluorotellurite-germanate glasses. An intense ~3 μm emission with a full width at half maximum (FWHM) of 245 nm is achieved in the Er3+/Ho3+/Yb3+ triply-doped fluorotellurite-germanate glass upon excitation at 980 nm. The glass not only possesses considerably low OH− absorption coefficient (0.189 cm−1), but also exhibits low phonon energy (704 cm−1). Moreover, the measured lifetime of Ho3+: 5I6 level is as high as 0.218 ms. In addition, the energy transfer rate to hydroxyl groups and quantum efficiency (η) of 5I6 level were calculated in detail by fitting the variations of lifetimes vs. the OH− concentrations. The formation ability and thermal stability of glasses have been improved by introducing GeO2 into fluorotellurite glasses. Results reveal that Er3+/Ho3+/Yb3+ triply-doped fluorotellurite-germanate glass is a potential kind of laser glass for efficient 3 μm laser.

Emission properties of 1.8 and 2.3 μm in Tm3+-doped fluoride glass

In this work a Tm3+-doped fluoride glass with good thermal stability is prepared. Intensive 1.8 and 2.3 μm emissions are obtained when pumped by an 800 nm laser diode. And the 1.48 μm emission is limited because of the much strong radiation around 1.8 μm. On the basis of absorption spectrum, radiative properties are investigated and discussed according to Judd–Ofelt parameters (Ω2, Ω4, Ω6) calculated by Judd–Ofelt theory. Besides, absorption and emission cross-sections of 3F4 → 3H6 transition are figured out and analyzed by using McCumber and Beer–Lambert theories. The high gain around 1.8 μm was predicted by the large σemiτrad product (29.8 × 10–21 cm2 ms). The results obtained indicate that the Tm3+-doped fluoride glass can be a promising 2.0 μm laser glass material.