Abstract
We have developed a method for fabricating thin layers of Ce3+ doped yttrium aluminium garnet, Y3Al5O12 (YAG:Ce) based on a sol-gel approach with propylene oxide as a gelation initiator. A single spin-coating process followed by a sequence of heat treatments allows the fabrication of polycrystalline YAG:Ce thin layers with a thickness of a few hundreds of nanometers. Surface morphology, crystallite size, and quantum efficiency are examined as a function of heat treatment temperature. The optical quality of the layer is further investigated by measuring the enhanced absorption of light coupled into the layer. We fabricate a three-layered slab waveguide system consisting of a fused silica glass substrate, a YAG:Ce layer and a SiO2 upper layer, and excite the system by illumination through a prism. The incident light couples to the fundamental waveguide mode in the YAG:Ce layer where it is eventually absorbed, resulting in an enhancement of absorption by a factor of 30. In correspondence, we observe a similar increase in emission intensity of photoluminescence caused by the enhanced absorption.
Highlights
Ce3+ doped yttrium aluminium garnet, Y3Al5O12 (YAG:Ce) is an important phosphor because of its excellent luminescent properties, chemical durability, and thermal stability
We have developed a method for fabricating thin layers of Ce3+ doped yttrium aluminium garnet, Y3Al5O12 (YAG:Ce) based on a sol-gel approach with propylene oxide as a gelation initiator
A single spin-coating process followed by a sequence of heat treatments allows the fabrication of polycrystalline YAG:Ce thin layers with a thickness of a few hundreds of nanometers
Summary
Ce3+ doped yttrium aluminium garnet, Y3Al5O12 (YAG:Ce) is an important phosphor because of its excellent luminescent properties, chemical durability, and thermal stability. The absorption length of YAG:Ce with a typical Ce3+ concentration less than 1 mol% is on the order of 100 μm for light with a wavelength around 450 nm [10,11] This results in a reduction of such blue light due to absorption by a factor 1/e over a distance of 100 μm in a non-scattering YAG:Ce layer. An alternative to increase the absorption in thin layers of YAG:Ce is to couple the blue light into waveguide modes that propagate inside the layer. The absorption is increased by a factor of 30, and enhanced emission is observed as a result of the increased absorption This enhanced absorption and emission demonstrate the high optical quality of the films and open new possibilities for efficient light conversion in thin layers of YAG:Ce
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