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Proceedings Paper

Intense photoluminescence and optical gain in rare-earth doped Polycrystalline Sapphire: a new bulk media for high-power phosphors and high-energy lasers
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Paper Abstract

Conventional materials engineering approaches for polycrystalline ceramic gain media rely on optically isotropic crystals with high equilibrium solubility of luminescent rare-earth (RE) ions. Crystallographic optical symmetry is traditionally relied upon to avoid scattering losses caused by refractive index mismatch at grain boundaries in randomly oriented anisotropic crystals and high-equilibrium RE-solubility is needed to produce sufficient photoluminescence (PL) for amplification and oscillation. These requirements exclude materials such as polycrystalline sapphire/alumina that have significantly superior thermo-mechanical properties (Rs~19,500Wm-1), because it possesses 1) uxiaxial optical properties that at large grain sizes, result in significant grain boundary scattering, and 2) a very low (~10-3%) RE equilibrium solubility that prohibits suitable PL. I present new materials engineering approaches operating far from thermodynamic equilibrium to produce a bulk Nd:Al2O3 medium with optical gain suitable for amplification/lasing. The key insight relies on tailoring the crystallite size to the other important length scales-wavelength of light and interatomic dopant distances and show that fine crystallite sizes result in sufficiently low optical losses and over-equilibrium levels of optically active RE-ions, the combination of which results in gain. The emission bandwidth is broad, ~13THz, a new record for Nd3+ transitions, enabling tuning from ~1050nm-1100nm and/or ultra-short pulses in a host with superior thermal-mechanical figure of merit. Laser grade Nd:Al2O3 opens a pathway for lasers with revolutionary performance.

Paper Details

Date Published: 4 September 2018
PDF: 13 pages
Proc. SPIE 10755, Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications XII, 1075509 (4 September 2018); doi: 10.1117/12.2322108
Show Author Affiliations
E. H. Penilla, Advanced Materials Processing and Synthesis Lab. (United States)
Univ. of California, San Diego (United States)
L. F. Devia-Cruz, Advanced Materials Processing and Synthesis Lab. (United States)
M. A. Duarte, Advanced Materials Processing and Synthesis Lab. (United States)
Univ. of California, San Diego (United States)
C. L. Hardin, Advanced Materials Processing and Synthesis Lab. (United States)
Y. Kodera, Advanced Materials Processing and Synthesis Lab. (United States)
Univ. of California, San Diego (United States)
J. E. Garay, Advanced Materials Processing and Synthesis Lab. (United States)
Univ. of California, San Diego (United States)


Published in SPIE Proceedings Vol. 10755:
Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications XII
Shizhuo Yin; Ruyan Guo, Editor(s)

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