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Upconversion effect on fluorescence quantum efficiency and heat generation in Nd3+-doped materials
Optics Express
|June 5, 2009
Summary
Energy transfer upconversion (ETU) in Nd3+-doped materials significantly reduces fluorescence quantum efficiency at high concentrations and excitation power. The thermal lens technique effectively measures these effects, revealing concentration-dependent critical inversion density.
Area of Science:
- Materials Science
- Spectroscopy
- Laser Physics
Background:
- Energy transfer upconversion (ETU) is crucial in rare-earth-doped materials, affecting optical properties.
- Fluorescence quantum efficiency (eta) is a key parameter influenced by non-radiative processes like ETU.
- Nd3+-doped materials are widely used in lasers and optical devices, making their efficiency critical.
Purpose of the Study:
- To experimentally determine the influence of energy transfer upconversion (ETU) on fluorescence quantum efficiency (eta) in Nd3+-doped materials.
- To investigate the role of energy migration in upconversion losses.
- To re-evaluate the concentration dependence of critical inversion density.
Main Methods:
- Utilized the thermal lens (TL) technique for sensitive measurements.
- Investigated Nd3+-doped materials with varying concentrations.
- Analyzed the impact of excitation power on fluorescence quantum efficiency.
Main Results:
- A significant reduction in eta was observed with increasing excitation power in high Nd3+ concentration samples due to efficient ETU.
- Energy migration was identified as the primary mechanism responsible for upconversion losses.
- The critical inversion density was found to decrease with increasing Nd concentration, contradicting previous assumptions.
Conclusions:
- The thermal lens technique is a sensitive and valuable method for studying ETU processes.
- Measurements can be performed at pump power regimes that prevent material damage.
- Understanding ETU and energy migration is essential for optimizing Nd3+-doped materials for optical applications.
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