Optical Sciences

Biomolecules and nanostructures

The Optical Sciences group studies the interaction of light and matter. Our current focus is on detection and sensing/imaging with an emphasis on the development of integrated photonics. We are part of Twente University's Department of Science and Technology and member of the MESA+ institute.


Direct confocal lifetime measurements on rare-earth-doped media exhibiting radiation trapping

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Yean-Sheng Yong, Shanmugam Aravazhi, Sergio A. Vázquez-Córdova, Joan J. Carvajal, Francesc Díaz, Jennifer L. Herek, Sonia M. García-Blanco, and Markus Pollnau
Optical Materials Express
Vol. 7, No. 2 Feb 1, 2017

Radiation trapping occurs in rare-earth-doped active media with strong spectral overlap of luminescence and ground-state absorption. It is demonstrated experimentally that a confocal measurement mitigates the influence of radiation trapping on the measured luminescence lifetime, hence allowing for direct extraction of the lifetime from the measured decay curves. The radiation trapping effect is largely suppressed by probing a small sample volume and rejecting the photons reemitted from the unpumped region. This non-destructive measurement method is applied to ytterbium (Yb3+) activated potassium double tungstate crystalline layers with Yb3+ concentrations ranging from 1.2 at.% up to 76 at.% (~8X1019 - 5X1021 cm-3). The measured lifetime values are comparable to the results reported for Yb3+-doped potassium double tungstate powder diluted in liquid.
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