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DOE OSTI2020

Materials Data on La2Be2O5 by Materials Project

La2Be2O5 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Be2+ is bonded to four O2- atoms to form corner-sharing BeO4 tetrahedra. There are a spread of Be–O bond distances ranging from 1.61–1.70 Å. La3+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of La–O bond distances ranging from 2.42–3.02 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Be2+ and four equivalent La3+ atoms. In the second O2- site, O2- is bonded in a distorted linear geometry to two equivalent Be2+ and four equivalent La3+ atoms. In the third O2- site, O2- is bonded in a 1-coordinate geometry to one Be2+ and four equivalent La3+ atoms. In the fourth O2- site, O2- is bonded in a distorted linear geometry to two equivalent Be2+ and four equivalent La3+ atoms.

36 MATERIALS SCIENCE↗

NASA NTRS1995

Laser-Induced Photochromic Centers in Ce(3+):La2Be2O5

Intense 355-nm excitation of the lowest 4f to 5d transition of Ce(3+):La2Be2O5 leads to a brownish coloration of the crystal due to the formation of stable photochromic centers. These centers are characterized by a broadband absorption spectrum that spans the 220-840 nm spectral range. Since they can be readily bleached by optical excitation into their absorption band, the centers are photochromic. They are produced by a two-step photoionization of Ce(3+) ions followed by attachment of the detached electrons at trapping sites in the crystal. The dependence of the number of centers on laser intensity and length of exposure have been measured, and the kinetics of growth have been studied.

Cheung, Y. M.↗

NASA NTRS1981

Repetitive Q-switched operation of x-axis Nd:La2Be2O5

The repetitive Q-switched performances of an x-axis neodymium-doped lanthanum beryllate (Nd:BeL) laser and the current state-of-the-art Nd:YAG laser are compared. Output beam pulse energy, peak power, pulse width, beam divergence and mode pattern were measured for a gold-plated single elliptical cavity using a xenon flashlamp for excitation. The output of the Nd:BeL laser is found to exceed that of the Nd:YAG laser by a factor of two at Q-switched repetition rates on the order of 1 Hz, due to the smaller stimulated emission cross section of the x-axis Nd:BeL. When the repetition rate is increased to 10 Hz, the Nd:BeL output falls to a level three fifths lower than its low-rate value, while Nd:YAG output remained essentially constant. Analysis reveals that the decrease in output may be attributed to a depolarization loss due to thermally induced stress birefringence.

Tucker, A. W.↗

NASA NTRS1992

Optimization of rod diameter in solid state lasers side pumped with multiple laser diode arrays

Results of a study to determine the optimum laser rod diameter for maximum output energy in a solid state neodymium laser transversely pumped with multiple laser diode arrays are reported here. Experiments were performed with 1.0 mm, 1.5 mm and 2.0 mm rod radii of both neodymium doped Y3Al5O12 (Nd:YAG) and La2Be2O5 (Nd:BeL) pumped with laser diode arrays having a maximum combined energy of 10.5 mJ. Equations were derived which predict the optimum rod radius and corresponding output mirror reflectivity for a given laser material and total pump energy. Predictions of the equations agreed well with the experiments for each of the laser materials which possessed significantly different laser properties from one another.

Sims, Newton, Jr.↗