The composition and properties of neodymium-doped (Nd-doped) phosphate glasses used for simultaneous high-energy (10 3 –10 6 J) and high-peak-power (10 12 –10 15 W) laser applications such as fusion energy research, are reviewed. The most common base glasses are meta-phosphates (O/P ∼3) with the approximate composition: 60P 2 O 5 –10Al 2 O 3 –30M 2 O/MO; K/Ba or K/Mg are typical modifiers. The spectroscopy of Nd 3+ in these glasses is well understood and laser properties can be accurately determined from measured spectroscopic properties. The major mechanisms for Nd 3+ non-radiative relaxation are reviewed and empirical expressions are presented that predict these effects in phosphate glasses. Optical and thermal–mechanical properties have been measured on a number of laser glasses and can be correlated with composition. Sub-critical crack growth rates in stress regions I, II and III have been reported for the first time in phosphate laser glasses. The mechanism for Pt inclusion formation and dissolution has been studied leading to damage resistant (Pt-inclusion-free) laser glasses.

Nd-doped phosphate glasses for high-energy/high-peak-power lasers

The composition and properties of neodymium-doped (Nd-doped) phosphate glasses used for simultaneous highenergy (10 3 ‐10 6 J) and high-peak-power (10 12 ‐10 15 W) laser applications such as fusion energy research, are reviewed. The most common base glasses are meta-phosphates (O/P3) with the approximate composition: 60P2O5‐10Al2O3‐ 30M2O/MO; K/Ba or K/Mg are typical modifiers. The spectroscopy of Nd 3a in these glasses is well understood and laser properties can be accurately determined from measured spectroscopic properties. The major mechanisms for Nd 3a non-radiative relaxation are reviewed and empirical expressions are presented that predict these eAects in phosphate glasses. Optical and thermal‐mechanical properties have been measured on a number of laser glasses and can be correlated with composition. Sub-critical crack growth rates in stress regions I, II and III have been reported for the first time in phosphate laser glasses. The mechanism for Pt inclusion formation and dissolution has been studied leading to damage resistant (Pt-inclusion-free) laser glasses. ” 2000 Elsevier Science B.V. All rights reserved.

Section 3. Applications Nd-doped phosphate glasses for high-energy/high-peak-power lasers

Publisher Summary The intensities of intraconfigurational f–f transitions are reviewed in the chapter The chapter presents the transition mechanisms for lanthanide ions—namely, the magnetic dipole transition, the induced electric dipole transition, and the electric quadrupole transition It discusses the way experimental intensities can be determined from the spectra The chapter also focuses on the expression of the dipole strength and the oscillator strength in oriented and in randomly-oriented systems Correction factors for lanthanide ions in a dielectric medium are described in the chapter Although only a few magnetic dipole transitions exist for the trivalent lanthanide ions, magnetic dipole transitions are of interest, because their intensities are in a first approximation independent of the ligand environment and can, thus, be used as intensity standards The intensity of a magnetic dipole transition can be calculated exactly, provided that suitable wavefunctions are available These wavefunctions can be obtained from diagonalization of the energy matrix

Chapter 167 Spectral intensities of f-f transitions

A hermetically sealed glass package and method for manufacturing the hermetically sealed glass package are described herein using an OLED display as an example. Basically, the hermetically sealed OLED display is manufactured by providing a first substrate plate and a second substrate plate and depositing a frit onto the second substrate plate. OLEDs are deposited on the first substrate plate. An irradiation source (e.g., laser, infrared light) is then used to heat the frit which melts and forms a hermetic seal that connects the first substrate plate to the second substrate plate and also protects the OLEDs. The frit is glass that was doped with at least one transition metal and possibly a CTE lowering filler such that when the irradiation source heats the frit, it softens and forms a bond. This enables the frit to melt and form the hermetic seal while avoiding thermal damage to the OLEDs.

Glass package that is hermetically sealed with a frit and method of fabrication

The theoretically determined slope efficiency and threshold pump power for continuous wave (CW) operation of a Tm-doped silica fiber laser are presented. The associated rate equations are solved using standard techniques and, in conjunction with the published and our measured spectroscopic parameters as input, the model was used to examine the fiber laser output for a variety of fiber and pump configurations. After good agreement was achieved between the model calculations and the published experimental measurements, the model was used to examine the relative performance of the fiber laser when the pump wavelength was varied over the /sup 3/F/sub 4/, /sup 3/H/sub 5/, and /sup 3/H/sub 4/ absorption bands of Tm/sup 3+/. The calculated maximum slope efficiencies were determined to be /spl sim/40, /spl sim/57, and /spl sim/84%, respectively, for each of the /sup 3/F/sub 4/, /sup 3/H/sub 5/, and /sup 3/H/sub 4/ absorption band pump schemes and the threshold pump power over the range of pump schemes was determined to vary by only 28%. The model was further used to analyze the fiber laser output when the fiber length, Tm/sup 3+/ concentration and /sup 3/H/sub 4/ energy level lifetime were varied and the consequences on the operation of the fiber laser with these variations are discussed.

Theoretical modeling of Tm-doped silica fiber lasers

Optical properties, fluorescence mechanisms and energy transfer in Tm3+, Ho3+ and Tm3+ -Ho3+ doped near-infrared laser glasses, sensitized by Yb3+

Persistent spectral hole burning is observed in Sm2+-doped glasses at room temperature. The holes are burned in the 7F0 → 5D0, 5D1 lines of the Sm2+ ions in three kinds of fluoride glass. The dependence of the burning efficiency on the sample and on the burning intensity is measured. The intensity dependence is approximately linear, and no antihole is observed around the burned hole. The hole-burning mechanism is discussed. The temperature dependence of the homogeneous width is also measured.

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Room-temperature persistent spectral hole burning in Sm(2+)-doped fluoride glasses.

Gradient-index rod lenses with a parabolic-index profile have been fabricated by a double Na–Ag ion-exchange process, and their optical characteristics have been evaluated. The numerical aperture and minimum focused spot diameter of the 2-mm diam rod lens were 0.58 and 2.5 μm for λ = 0.63 μm, respectively. Because of the high diffusing rate for Ag ions, this technique offers the possibility of making large-sized (larger than 10 mm-diam) rod lenses for photographic uses.

Gradient-index rod lens made by a double ion-exchange process

The compositional dependences of spontaneous emission probabilities of rare-earth ions such as Nd3+ and Er3+ were studied for silicate, phosphate and borate glasses using the Judd-Ofelt theory. The effect of the covalency of the rare-earth ion sites on the emission probabilities was estimated from the variations of the profiles of the absorption spectra in terms of the nephelauxetic effect. The spontaneous emission probabilities which depended on the intensity parameters, Ω4 and Ω6, were strongly affected by the ionic packing ratio of the glass host.

Tetsuro Izumitani

Papers

Optical properties, fluorescence mechanisms and energy transfer in Tm3+, Ho3+ and Tm3+ -Ho3+ doped near-infrared laser glasses, sensitized by Yb3+

Room-temperature persistent spectral hole burning in Sm(2+)-doped fluoride glasses.

Gradient-index rod lens made by a double ion-exchange process

Correlation between radiative transition probabilities of rare-earth ions and composition in oxide glasses

Blue, green and 0.8 μm Tm3+, Ho3+ doped upconversion laser glasses, sensitized by Yb3+