Gain dynamics in a highly ytterbium-doped potassium double tungstate epitaxial layer

Yean Sheng Yong (Corresponding Author), Shanmugam Aravazhi, Sergio A. Vázquez-Córdova, Jennifer L. Herek, Sonia M. García-Blanco, Markus Pollnau

Research output: Contribution to journalArticleAcademicpeer-review

2 Citations (Scopus)

Abstract

Active media with high rare-earth concentrations are essential for small-footprint waveguide amplifiers. When operating at high population inversion, such devices are often affected by undesired energy-transfer processes and thermal effects. In this work, we study a 32-μm-thick epitaxial layer of KGd0.43Yb0.57WO42, representing an Yb3 concentration of ∼3.8 × 1021 cm−3, grown on an undoped KYWO42 substrate. The pump absorption, luminescence decay, and small-signal gain are investigated under intense pumping conditions. Spectroscopic signatures of an energy-transfer process and of quenched ions, as well as thermal effects, are observed. We present a gain model which takes into account excessive heat generated due to the abovementioned experimental observations. Based on finite-element calculations, we find that the net gain is significantly reduced due to, first, a fraction of Yb3 ions not contributing to stimulated emission, second, a reduction of population inversion owing to a parasitic energy-transfer process and, third, degradation of the effective transition cross-sections owing to device heating. Nevertheless, a signal enhancement of 8.1 dB was measured from the sample at 981 nm wavelength when pumping at 932 nm. The corresponding signal net gain of ∼800 dB∕cm, which was achieved without thermal management, is promising for a waveguide amplifier operating without active cooling.

Original languageEnglish
Pages (from-to)2176-2185
Number of pages10
JournalJournal of the Optical Society of America B: Optical Physics
Volume35
Issue number9
DOIs
Publication statusPublished - 21 Aug 2018

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tungstates
ytterbium
potassium
energy transfer
population inversion
temperature effects
pumping
amplifiers
waveguides
footprints
stimulated emission
ions
rare earth elements
signatures
luminescence
pumps
degradation
cooling
heat
heating

Cite this

Yong, Yean Sheng ; Aravazhi, Shanmugam ; Vázquez-Córdova, Sergio A. ; Herek, Jennifer L. ; García-Blanco, Sonia M. ; Pollnau, Markus. / Gain dynamics in a highly ytterbium-doped potassium double tungstate epitaxial layer. In: Journal of the Optical Society of America B: Optical Physics. 2018 ; Vol. 35, No. 9. pp. 2176-2185.
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Gain dynamics in a highly ytterbium-doped potassium double tungstate epitaxial layer. / Yong, Yean Sheng (Corresponding Author); Aravazhi, Shanmugam; Vázquez-Córdova, Sergio A.; Herek, Jennifer L.; García-Blanco, Sonia M.; Pollnau, Markus.

In: Journal of the Optical Society of America B: Optical Physics, Vol. 35, No. 9, 21.08.2018, p. 2176-2185.

Research output: Contribution to journalArticleAcademicpeer-review

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