Infrared-to-Visible Frequency up-Conversion in Trivalent Erbium Ions Doped Fluoride Glasses (ZnF_2-Al_F3-PbF_2-LiF)

High efficiency frequency up conversion in trivalent erbium ion doped new fluoride glass matrix (ZnF 2 AlF 3 PbF 2 LiF) was investigated. Under 950 nm laser diode excitation, the glasses gave very intense green, weak red and violet emissions. The up conversion mechanism is discussed. In addition, the infrared transmittance spectrum, the Raman spectrum and the lifetime of the trivalent erbium states in the samples were measured. The results illustrate the large potential of these new glasses for photonic applications.

Relationship between Composition, Density and Refractive Index for Heavy Metal Fluoride Glasses

The density and the refractive index for various compositions of heavy metal fluoride (HMF) glasses, used to make low loss optical wave guides, have been measured by standard archimedes method and by using as Pulfrich refractometer respectively. The density as a function of composition is calculated considering the effective volume of the ions contained in the glass to be invariant. The refractive index as a function of composition is also calculated, based on the Lorenz Lorentz equation, by computing the electronic polarizability of HMF glasses. All calculated results are in good agreement with the observed data.

S tudy on Doped Fluoride Glasses for Scintillation Applications

This paper studies the properties of fluoride glasses for use in particle calorimeters or in optical fibers. The effects of major and minor impurities in manufacturing process and ultimately on the glass properties have been investigated. Glasses in a range of compositions have been made and tested in the form of small samples as well as larger blocks of size 2×3×14 cm 3. Results of measurements on these materials, using a high energy particle beam, are presented.

FLUORIDE GLASSES CONTAINING RARE EARTH

Fluoride glasses containing rare earths exhibit interesting spectroscopic properties.They have wide transmission range from 0.25μm in the UV to 7μm in the IR,allowing observation,in a vitreous material,of absorption and emission bands in a large optical range.The absorption spectra of fluoride glasses with rare earth substitutions are found to vary with the rare earth ions used.The T_g~'s for these glasses average out at 311℃.Optical properties,such as refractive indices are not obviously influenced by rare earth substitutions.

Energy transfer mechanism in Er^(3+) doped fluoride glass sensitized by Tm^(3+) or Ho^(3+) for 2.7-μm emission

Enhanced 2.7 μm emission is obtained in Er3＋/Tma＋ and Era＋/Ho3＋ codoped ZBYA glasses. Absorp- tion and emission spectra are tested to characterize the 2.7 μm emission properties of Era＋/Tm3＋ and Era＋/Ho3＋ doped ZBYA glasses and a reasonable energy transfer mechanism of 2.7 μm emission between Er3＋ and Tm3＋Ho3＋） ion is proposed. Codoping of Tm3＋ or Ho3＋ significantly reduces the lifetime of the Era＋： 4I13/2 level due to the energy transfer of Er3＋：4I13/2 →Tm3＋：3F4 or Er3＋：4I13/2 →Ho3＋： 5I7. Thus, the 2.7μm emission is strengthened and the 1,5μm emission is decreased accordingly especially in the Era＋/Tma＋ sample. The upconversion effects between the Er3＋/Tm3＋ and Er3＋/Ho3＋ doped ZBYA glasses are different attribute to the different energy transfer efficiencies. Both of the two codoped samples possess nearly equal large emission cross section （16.6 × 10 -21 cm-2） around 2.7 μm. The results indicate that this Er3＋/Tm3＋ or Er3＋/Ho3＋ doped ZBYA glass has potential applications in 2.7 μm laser.

Studies on the Preparation and Properties of AIF_3－based Rare Earth Fluoride Glass

AlF3-REF3-AEF2 (RE: rare earth, AE: alkali earth) system fluoride glasses were prepared by quenching melts. The glass forming region of AlF3NdF3-(Mg0.25Ca0.25Sr0.25Ba0.25) F2 system was determined. Effects of AE and RE fluoride on the glass forming ability and thermal properties of the system have been discussed. The IR cut-off wavelength of AIF3-REF3-AEF3 glass is about 7 μm. This system has many advantages, such as low refractive index, high Abbe number, high Tg and Tc-Tg values, and good chemical durability, etc. This is a kind of new excellent ultra-low loss optical fiber and IR optical material.

Sensitized Up-Conversion Luminescence of Ho^(3+) in Nd^(3+)-Yb^(3+)-Ho^(3+) Co-doped ZrF_4-Based Glass

Up-conversion processes for the blue, green and red emissions were foundtwo-photon phenomenon, known as the cooperative phenomenon. This phenomenon was assisted by Nd^(3+)→ Yb^(3+) → Ho^(3+) energy transfer. The strong green emission due to the Ho^(3+) : (~5F_4, ~5S_2)→ ~5I_8 transitions was observed in Nd^(3+) - Ho^(3+) co-doped ZrF_4-based fluoride glasses under800 nm excitation. As an attempt to enhance Ho^(3+) up-conversion luminescences in the Nd^(3+) -Ho^(3+) co-doped ZrF_4-based glasses, Yb^(3+) ions were added to the glasses. As a result it wasfound that, in 800 nm excitation of 60ZrF_4. 30BaF2. (8-x)LaF_3. 1NdF_3. xYbF_3. 1HoF_3 glasses (x =0 to 7), sensitized up-conversion luminescences are observed at around 490 nm (blue), 545 nm(green), and 650 nm (red), which correspond to the Ho^(3+) : ~5F_3 → ~5I_8, ( ~5F_4, ~5S_2) →~5I_8 and ~5F_5 → ~5I_8 transitions respectively. The intensities of the green and red emissions ina 3 mol% YbF_3-containing glass were about 50 times stronger than those glasses without YbF_3. Thisis based on sensitization due to Yb^(3+) ions. In particular, the green emission was extremelystrong and the Nd^(3+) - Yb^(3+) - Ho^(3+) co-doped ZrF_4-based glasses have a high possibility ofrealizing a green up-conversion laser glass. In this paper the up-conversion mechanism in theglasses is discussed in detail.

Improved Fluorescence from Tm^3＋/Er^3＋/Ce^3＋ Triply Doped Bismuth-Silicate Glasses for S＋C-bands Amplifiers

Fluorescence of Tm^3＋/Er^3＋ codoped bismuth-silica （BS） glasses and the sensitization of Ce^3＋ are investigated, It shows that Ce^3＋ codoping with Tm^3＋/Er^3＋ in BS glasses results in a quenching of Tm^3＋ ion emission from ^3F4 to the ^3H6 level. Consequently, the 1.47μm emission occurs after the population inversion between the ^3H4 and ^3F4 levels. Furthermore, the codoped glasses show the broad emission spectra over the whole S and C bands with full-width at half-maximum （FWHM） up to about 119nm, as it combines 1.55μm emission band of Er^3＋ with 1.47μm emission band of Tm^3＋ under 800hm excitation.

Recent progress on upconversion luminescence enhancement in rare-earth doped transparent glass-ceramics

The upconversion（UC） of the rare earth doped glass-ceramics has been extensively investigated due to their potential applications in many fields, such as color display, high density memories, optical data storage, sensor and energy solar cell, etc. Many series of them, especially the oxyfluorides glasses containing Ba2 LaF 7 nanocrystals were studied in this review work, due to the thermal and mechanical toughness, high optical transmittance from the ultraviolet to the infrared regions, and a low nonlinear refractive index compared to the other commercial laser glasses. Moreover, the energy transfer（ET） between the rare earth ions and transition metals plays an important role in the upconversion process. The cooperative ET has been researched very activly in UC glasses due to applications in the fields of solar cells, such as in the Er/Yb, Tm/Yb, Tb/Yb, Tb/Er/Yb and Tm/Er/Yb couples. The present article reviews on the recent progress made on：（i） upconversion materials with fluoride microcrystals in glasses and the mechanisms involved, including the UC in double and tri-dopant RE ions activated fluoride microcrystal, energy transfer process; and（ii） the effect of the metal Mn and nanoparticles of Au, Ag, Cu on the enhancement of UC emissions. Discussions have also been made on materials, material synthesis, the structural and emission properties of glass-ceramics. Additionally, the conversion efficiency is still a challenge for the spectra conversion materials and application; challenge and future advances have also been demonstrated.