Temperature-dependent absorption and emission of potassium double tungstates with high ytterbium content
2016 (English)In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 24, no 23, 26825-26837 p.Article in journal (Refereed) Published
We study the spectroscopic properties of thin films of potassium ytterbium gadolinium double tungstates, KYb0.57Gd0.43(WO4)(2), and potassium ytterbium lutetium double tungstates, KYb0.76Lu0.24(WO4)(2), specifically at the central absorption line near 981 nm wavelength, which is important for amplifiers and lasers. The absorption cross-section of both thin films is found to be similar to those of bulk potassium rare-earth double tungstates, suggesting that the crystalline layers retain their spectroscopic properties albeit having >50 at.% Yb3+ concentration. The influence of sample temperature is investigated and found to substantially affect the measured absorption cross-section. Since amplifiers and lasers typically operate above room temperature due to pump-induced heating, the temperature dependence of the peak-absorption cross-section of the KYb0.57Gd0.43(WO4)(2) is evaluated for the sample being heated from 20 degrees C to 170 degrees C, resulting in a measured reduction of peak-absorption cross-section at the transitions near 933 nm and 981 nm by similar to 40% and similar to 52%, respectively. It is shown that two effects, the change of Stark-level population and linewidth broadening due to intra-manifold relaxation induced by temperature-dependent electronphonon interaction, contribute to the observed behavior. The effective emission cross-sections versus temperature have been calculated. Luminescence-decay measurements show no significant dependence of the luminescence lifetime on temperature.
Place, publisher, year, edition, pages
Optical Society of America, 2016. Vol. 24, no 23, 26825-26837 p.
Atom and Molecular Physics and Optics
IdentifiersURN: urn:nbn:se:kth:diva-198571DOI: 10.1364/OE.24.026825ISI: 000388414600083PubMedID: 27857411OAI: oai:DiVA.org:kth-198571DiVA: diva2:1057729
QC 201612192016-12-192016-12-192016-12-19Bibliographically approved