ISBN 9783843927635

978-3-8439-2763-5, Reihe Physik

Daniel-Timo Marzahl
Rare-Earth-Doped Strontium Hexaaluminate Lasers

157 Seiten, Dissertation Universität Hamburg (2016), Softcover, A5

Zusammenfassung / Abstract

In the framework of this thesis rare-earth-doped SrAl12O19 (SRA) was investigated. This host material is of interest especially due to its low crystal field depression and low maximum phonon energy. The investigations include the growth of the crystals as well as the spectroscopic properties and laser characteristics. Thereby the main focus was kept on the visible spectral range. For this purpose the following rare-earth ions were utilized in their trivalent state: praseodymium (Pr3+), samarium (Sm3+), terbium (Tb3+), and dysprosium (Dy3+). Furthermore, trivalent neodymium (Nd3+) was employed and investigated in the near infrared spectral range.

The crystal quality of SRA was investigated and optimized under Pr 3+ -doping. For charge compensation Mg2+ is often codoped. In this thesis the amount of Mg2+ was varied and Na+ was introduced as an alternative codoping. No significant changes were observed in spectroscopic investigations. However, the effect of the charge compensation on the laser characteristics was demonstrated. In further laser experiments with Pr,Mg:SRA a total tunability of ≈1100 cm−1 was realized in several smaller ranges in the orange to deep red spectral range.

With Nd,Mg:SRA laser action was achieved at 1051 nm with a slope efficiency of 62 % with respect to the absorbed pump power. Furthermore, to the best of the author’s knowledge laser operation of this crystal system was demonstrated for the first time at 900 nm and 1.3 µm.

The spectroscopic investigations with Sm3+-doped, Tb3+-doped, and Dy3+-doped SRA revealed peak ground state absorption and peak stimulated emission cross sections in the order of 10−21 cm2 . These are at least one order of magnitude smaller compared to Pr3+-doped and Nd3+-doped SRA. This can be attributed to a spin-flip, which is required for the investigated transitions in Sm3+, Tb3+, and Dy3+.

Laser operation of Sm,Mg:SRA was realized at 593 nm and 703 nm. To the best of the author’s knowledge this represents the first demonstration of laser operation of any Sm3+-doped oxide host material. The laser operated in a self-pulsing regime with a Q-switching like behavior. Due to computer simulations this effect is likely caused by saturable excited state absorption.