Doped Fluorophosphate Glasses Research Articles

Engineering rare-earth ions doped fluorophosphate glass for 1.47 μm lasers

This work reports the observation of a broadband emission at 1.47μm from Tm3+ and Tm3+/Ho3+ doped fluorophosphate glass. Radiative properties were calculated using the Judd–Ofelt theory. It should be noted that the prepared glasses exhibit broad 1.47μm with a full width at half-maximum (FWHM) of 110–121nm upon excitation of a conventional 790nm laser diode. The proper incorporation of Ho3+ into Tm3+-doped fluorophosphate glass could significantly enhance the 1.47μm emission intensity. Besides, energy transfer mechanism and microparameters are investigated. Prepared fluorophosphate glasses may be potentially useful engineering materials for 1.47μm lasers because of their advantageous spectroscopic characteristics and good thermal stability.

Fluorescence characteristics and energy transfer of ytterbium-sensitized erbium-doped fluorophosphate glass for amplifier applications

Yb3+/Er3+ codoped fluorophosphate glass has been investigated for developing broadband waveguide amplifier application. Spectroscopic properties and energy transfer microparameters of prepared glasses have been discussed. The spectral components of 1.55μm emission are analyzed and an equivalent four-level system is proposed to estimate the stark splitting for the 4I15/2 and 4I13/2 levels in Er3+ doped fluorophosphate glass. The results indicate that highly doped Yb3+ ions could transfer energy to Er ions efficiently in fluorophosphate glass and Er3+/Yb3+ doped fluorophosphate glass is preferable for broadband Er3+-doped waveguide amplifier application.

Optical properties of Yb3+ ions in fluorophosphate glasses for 1.0 μm solid-state infrared lasers

Yb3+-doped fluorophosphate glasses were prepared by melt-quenching technique and characterized their spectroscopic properties to assess the laser performance parameters. The magnitude of absorption (emission) cross-sections at 975 nm for all the studied Yb3+-doped glasses is found to be in the range of 0.29–1.50 × 10−20 (0.59–1.99 × 10−20 cm2) which is much higher than those of commercial Kigre QX/Yb: 1.06 × 10−20 (0.5 × 10−20 cm2) laser glass. The luminescence lifetimes of 2F5/2 level decrease (1.15–0.45 ms) with increase in Yb2O3 concentration (0.1–4.0 mol%). Effect of OH− content on luminescence properties of Yb3+ ions has also been investigated. The effect of radiative trapping has been discussed by using McCumber (McC) and Fuchtbauer–Ladenburge (F–L) methods. The product of experimental lifetimes and emission cross-sections for 0.1 mol% Yb2O3-doped glass is found to be 2.28 × 10−20 cm2 ms which indicates that the higher energy storage and extraction capability could be possible. The detailed spectroscopic results suggest that the studied glasses can be considered for high-power and ultrashort pulse laser applications.

Optical absorption and near infrared emissions of Nd3+ doped fluorophosphate glass

Fluorophosphate glass doped with Nd3+ has been synthesized with low OH content. Near infrared emissions centered around 0.9, 1.06, and 1.3μm have been successfully obtained in present glass excited by a conventional 800nm laser diode. Based on the absorption spectrum, radiative properties were calculated and discussed using the Judd–Ofelt theory. The luminescence characteristics and energy transfer mechanism were investigated. Desirable low OH− concentration and spectroscopic characteristics of Nd3+-doped fluorophosphate glass indicate that it is a promising material for near-infrared lasers.

Synthesis and spectroscopic characterization of Ho3+/Tm3+/Pr3+ doped fluorophosphate glass

Fluorophosphate glass triply doped with Ho3+/Tm3+/Pr3+ has been synthesized. 2.86, 2 and 1.47 μm emissions have been successfully obtained from the present glass pumped by conventional 800 nm LD. The corresponding energy transfer mechanisms and microparameters are discussed and analyzed according to the photoluminescence performance and absorption measurements. Tm3+ ions can absorb the pumping energy and transfer it to Ho3+ and Pr3+ ions. Large energy transfer coefficient from Ho3+ to Pr3+ ions (8.22 × 10−39 cm6/s) has been obtained based on the Forster-Dexter theory. The results suggest Ho3+/Tm3+/Pr3+ triply doped fluorophosphate glass is a promising candidate for efficient mid-infrared laser.

Fluorescence properties and energy transfer study of Er3+/Nd3+ doped fluorophosphate glass pumped at 800 and 980 nm for mid-infrared laser applications

The fluorescence properties of 2.7 μm emission as well as near infrared emissions in Er3+/Nd3+ doped fluorophosphate glasses are investigated under 800 and 980 nm excitation. The fluorescence dynamics and energy transfer processes between Er and Nd ions in different pumping schemes are reported. Three Judd-Ofelt intensity parameters, energy transfer microparameters, and efficiency have been determined using the Judd-Ofelt and Förster-Dexter theories. The calculated energy transfer efficiency of the Er3+:4I13/2 level to the Nd3+:4I15/2 level is as high as 83.91%. The results indicate that Nd3+ may be an efficient sensitizer for Er3+ to obtain mid-infrared emission and the more suitable pumping scheme of 2.7 μm laser applications for Er3+/Nd3+ doped fluorophosphate glass is 980 nm excitation.

Mid-infrared luminescence and energy transfer of Dy3+/Tm3+ doped fluorophosphate glass

This work reports the observation of emissions at 2.9μm, 1.8μm and 1.47μm from Dy3+/Tm3+ codoped fluorophosphate glass upon excitation of a conventional 800nm laser diode. Judd–Ofelt intensity parameters and radiative properties of Dy3+ ions in present glasses were calculated using the Judd–Ofelt theory. The mechanism and microparameters of energy transfer processes were investigated based on photoluminescence performance and lifetime measurements. The Dy3+/Tm3+ codoped fluorophosphate glass possessing advantageous spectroscopic characteristics as well as excellent thermal stability is a promising candidate for an efficient 2.9μm laser.

Mid-infrared luminescence and energy transfer of Tm3+/Yb3+ doped fluorophosphate glass

Tm3+/Yb3+-codoped fluorophosphate glass is prepared by conventional melt-quenching method and the thermal stability of the glass is analyzed. The Judd–Ofelt parameters, radiation emission rates, radiative lifetime and branching ratios of prepared samples are calculated based on the absorption spectra. Upon excitation of a conventional 980nm laser diode, 1.8μm emission is obtained from Yb3+/Tm3+ codoped fluorophosphate. Additionally, the energy transfer between Yb3+ and Tm3+ ions are quantitatively analyzed. Hence, this Yb3+/Tm3+ codoped fluorophosphate glass possessing high energy transfer efficiency and excellent thermal stability is a good candidate for efficient 1.8μm laser.

Yb3+ doped fluorophosphate laser glasses with high gain coefficient and improved laser property

Yb3+ doped fluorophosphate glasses with high stimulated emission cross-section, large gain coefficient and low hydroxyl absorption coefficient were prepared by high temperature melting for fiber laser applications, and their spectral, general laser parameters were investigated accordingly by means of fluorescence emission spectrum, decay cure and infrared absorption spectra. Compared with previously reported fluorophosphate glasses, the investigated fluorophosphate glasses have highest grain coefficient and maintain a maximum laser systematical factor over other various types of laser glasses. The introduction of fluorides to fluorophosphate glasses results in the low level of hydroxyl absorption coefficient and concentration. All these advantages might mean that Yb3+ doped fluorophosphate glasses are a good candidate as an active laser media for short pulse, high power laser generation used for next generation nuclear fusion.

Comparative investigation on the 2.7 μm emission in Er3+/Ho3+ codoped fluorophosphate glass

104 times higher Er3+:2.7 μm fluorescence was observed when Ho3+ was added into an Er3+ doped fluorophosphate glass under 976 nm excitation. Obviously changed J-O parameters and the calculated spectroscopic properties of Er3+ prove that Ho3+ influences the local environment of Er3+ greatly. Increased upconversion luminescence around 550 nm and 658 nm shows that heat generation rises with Ho3+ introduction. Complicated energy transfer processes exist in this codoping situation and interactions among the excessive Ho3+ ions are considered as the dominant energy loss mechanisms, otherwise, the sensitizing effect from Ho3+ to Er3+ is very high if Ho3+:Er3+ ratio below 4. All the calculated results coincide well with the measured ones. Excellent 2.7 μm spectroscopic property, Raman analysis, together with the outstanding glass forming ability identify that this Er3+/Ho3+ codoped fluorophosphate glass can be effectively used for Er3+:2.7 μm fiber laser.

Effect of chloride ion introduction on structural and 15 μm emission properties in Er^3+-doped fluorophosphate glass: publisher’s note

In [J. Opt. Soc. Am. B28, 1638 (2011)] the wrong version of Fig. 4 was published; a duplicate of Fig. 1 was given. The figure has been corrected online as of September 26, 2011: http://www.opticsinfobase.org/josab/abstract.cfm?URI=josab‐28‐7‐1638.

Spatially resolved measurement of high doses in microbeam radiation therapy using samarium doped fluorophosphate glasses

The measurement of spatially resolved high doses in microbeam radiation therapy has always been a challenging task, where a combination of high dose response and high spatial resolution (microns) is required for synchrotron radiation peaked around 50 keV. The x-ray induced Sm3+ → Sm2+ valence conversion in Sm3+ doped fluorophosphates glasses has been tested for use in x-ray dosimetry for microbeam radiation therapy. The conversion efficiency depends almost linearly on the dose of irradiation up to ∼5 Gy and saturates at doses exceeding ∼80 Gy. The conversion shows strong correlation with x-ray induced absorbance of the glass which is related to the formation of phosphorus-oxygen hole centers. When irradiated through a microslit collimator, a good spatial resolution and high “peak-to-valley” contrast have been observed by means of confocal photoluminescence microscopy.

Intense 27 μm and broadband 20 μm emission from diode-pumped Er^3+/Tm^3+/Ho^3+-doped fluorophosphate glass

This Letter reports intense emission at 2.7 μm and broadband emission at 2.0 μm from Er(3+)/Tm(3+)/Ho(3+)-doped fluorophosphate glass. The fluorescence characteristics and energy transfer upon excitation of a conventional 980 nm laser diode are investigated. Based on the fluorescence spectra and lifetime measurement, the effect of Tm(3+) and Ho(3+) ions on intense 2.7 μm emission in fluorophosphate glass is demonstrated. It is also found that the effective bandwidth of 2.0 μm emission due to Tm(3+) and Ho(3+) ions can reach as high as 196 nm. These results indicate that the advantageous spectroscopic characteristics of Er(3+)/Tm(3+)/Ho(3+) triply doped fluorophosphate glass together with the outstanding thermal properties may become an attractive host for the mid-IR solid state lasers.

Intense 2.0 μm emission properties and energy transfer of Ho3+/Tm3+/Yb3+ doped fluorophosphate glasses

Intense 2.0 μm emission has been obtained from Ho3+/Tm3+/Yb3+ triply doped fluorophosphate glass pumped by a conventional 980 nm laser diode. The spectroscopic properties and energy transfer mechanisms between Ho3+, Tm3+ and Yb3+ are analyzed. Based on the absorption spectra, the Judd-Ofelt parameters, radiation emission rates, radiative lifetime and branching ratios of Ho3+ ions are calculated. It is also found that the 2.0 μm emission of Ho3+ can be greatly enhanced under the excitation at 980 nm by incorporating Tm3+ and Yb3+ simultaneously. Additionally, the micro-parameters of the energy transfer processes are quantitatively analyzed. The energy transfer coefficient from Yb3+ to acceptors and from Tm3+ to Ho3+ can reach as high as 13.14 × 10−40 cm6/s and 23.39 × 10−40 cm6/s, respectively. This Ho3+/Tm3+/Yb3+ doped fluorophosphate glass possessing high energy transfer coefficient and excellent thermal stability is a promising candidate for efficient 2.0 μm laser.

Effect of chloride ion introduction on structural and 15 μm emission properties in Er^3+-doped fluorophosphate glass

Effects of chloride ion introduction on structural and 1.5 μm emission properties in Er3+-doped fluorophosphate have been investigated. The structural changes revealed by the measured Raman spectra indicate that the chloride ions have an important influence on the phonon density of host glasses. With increasing chloride content, the phonon density of fluorophosphate glasses decreases. The chloride modified fluorophosphate glasses possessing higher thermal stability are suitable for broadband amplifier fiber fabrication. Desirable thermal resistance properties and spectroscopic characteristics of Er3+-doped chloride fluorophosphate glass indicate that it is a promising material for 1.5 μm lasers.

Enhanced effect of Ce3+ ions on 2 μm emission and energy transfer properties in Yb3+/Ho3+ doped fluorophosphate glasses

Effect of Ce3+ ions introduction on 2 μm emission properties and energy transfer mechanism in Yb3+/Ho3+-doped fluorophosphate glass has been investigated. From the measured fluorescence spectra, strong emission near 2 μm is demonstrated due to the sensitization of Yb3+ and Ce3+. Based on the absorption spectra, the Judd-Ofelt parameters and radiative properties were calculated and compared with those of other glass hosts. In addition, the energy transfer coefficient from Yb3+ to Ho3+ is 9.52 × 10−40 cm6/s in Yb3+/Ho3+/Ce3+ triply doped sample and is three times larger than that in undoped Ce3+ sample. These results suggest that this Yb3+/Ho3+/Ce3+ fluorophosphate glass with excellent thermal stability and efficient energy transfer from Yb3+ to Ho3+ is a good candidate for 2 μm laser.

Pressure-dependent fluorescence studies of Sm3+-doped fluorophosphate glass

Pressure-induced luminescence spectra and decay curves for the 4G5/2 level of Sm3+ ions in fluorophosphate glass (PKFBASm 40:54 P2O5+14 K2O+13 BaO+6 KF+9 Al 2 O 3+4 Sm 2O 3) have been measured as a function of pressure up to 36.3 GPa at room temperature. In this pressure range, a red shift of barycenter and Stark level splittings are observed for the 4G5/2→6HJ (J=9/2, 7/2 and 5/2) multiplet transitions. The decay curves of the 4G5/2 level show non-exponential behavior in the entire pressure range, which has been explained by energy transfer due to the dipole–dipole interaction. The effect of releasing pressure on the luminescence spectra and decay curves has also been studied. The results obtained for this glass have been compared with Sm3+-doped fluorophosphate, phosphate, lead phosphate, lithium borate and tellurite glasses.

Enhanced 2 μm emission of Yb–Ho doped fluorophosphates glass

In this paper, 2 μm emission spectra of Yb–Ho doped fluorophosphate glass are investigated and compared with Yb–Tm–Ho doped fluorophosphate glass. The 2 μm emission intensity of Yb–Ho doped fluorophosphate glass is much stronger than that of Yb–Tm–Ho doped fluorophosphate glass, exhibiting that Yb–Ho doping is an appropriate doping system to 2 μm application. As the doping concentration of Yb 3+ ions in Yb–Ho doped fluorophosphate glass increases, the 2 μm emission intensity increases monotonously and possesses a maximum for 10% Yb ions concentration. Therefore, 10% is the optimization of Yb ions doping concentration for 2 μm emission. Otherwise, the up-conversion emission of Ho 3+ ions is also studied. Combining with the energy transfer processes, the mechanism is discussed.

1.8 μ m emission of highly thulium doped fluorophosphate glasses

A new type of fluorophosphate glasses with high thulium doping concentration (up to 10 mol % Tm3+) is investigated. The intensive 1.8 μm fluorescence is demonstrated with lower concentration quenching. On the basis of the measured Raman spectroscopy, it is revealed that the glass structure will be changed when adding Tm3+ ions into fluorophosphate glasses. Besides, the Judd–Ofelt parameters and radiative properties are calculated and discussed based on Judd–Ofelt theory. And the absorption and emission cross-sections of F34→H36 transition are also calculated by using McCumber and Beer–Lambert theories.

2 μm Emission of Ho 3+-doped fluorophosphate glass sensitized by Yb 3+

Two micrometer emission of Ho 3+-doped new fluorophosphate glass sensitized by Yb 3+ upon excitation of a conventional 980 nm laser diode is reported. Based on the measured absorption spectra, the Judd–Ofelt parameters and radiative properties were calculated and discussed. For Yb 3+/Ho 3+ codoped fluorophosphate glass, the predicted spontaneous transition probability and emission cross-section of Ho 3+: 5I 7→ 5I 8 reaches 73.54 s −1 and 4.66 × 10 −21 cm 2 , respectively, are much higher than other reported glasses. Larger product of emission cross-section ( σ em ) and radiative lifetime ( τ rad ) in the prepared glass shows the prepared glass is expected to be better laser material. In addition, the σ em and maximum gain coefficient of Ho 3+ in Yb 3+/Ho 3+ codoped fluorophosphate glass is 12.02% and 12.12% larger than those of Ho 3+ singly-doped sample, respectively. The results suggest Yb 3+/Ho 3+ fluorophosphate glass is a good candidate for efficient 2 μm laser.