Epitaxial Growth of Single Crystal YAG for Optical Devices

Abstract

We report the latest progress on fabrication of rare earth doped single crystal yttrium aluminum garnet (YAG) core/undoped YAG cladded fibers. Rare-earth doped single crystal core fibers were grown with laser heated pedestal growth methods. In a second step, epitaxial methods were used to grow a single crystalline undoped YAG cladding onto the core fiber. Hydrothermal and liquid phase epitaxy methods utilize the core doped fiber as the seed. X-ray diffraction of cladding reveals an equilibrium (110) morphology. Energy-dispersive X-ray spectroscopy analysis shows there is minimal diffusion of rare-earth dopants into the cladding structure. The use of scandium doping is shown to substitute at the Al3+ site, thereby allowing an additional tunability of refractive index of core structure material besides conventional Y3+ site dopants. The use of these epitaxial growth methods enables material compatibility, tuning of refractive index, and conformal growth of cladding structures onto core fibers for optical devices.

Fabrication of Yb:YAG Transparent Ceramic by Vacuum Sintering Using Monodispersed Spherical Y2O3 and Al2O3 Powders

“…So, the ratio of the aggregate force to the mass is large for small particles. The agglomeration intensity σ can be expressed by Equation (11):…”

“…where S is saturation of the wetting liquid, θ is the degree of porosity and D refers to particle diameter. As shown in Equation (11), capillary tension has an obvious effect on the powder particle size under 100 µm.…”

“…There are many limitations such as low growth rate, high cost and the difficulty of obtaining a large size. As the YAG transparent ceramics have similar physical, chemical and laser properties with single crystal, it is preferred to prepare YAG ceramics with low cost and a high doping concentration of rare earth ions [10,11]. Since Ikesue prepared high-quality Nd:YAG transparent ceramics and used laser diode (LD) pumping to obtain laser output in 1995, YAG transparent ceramics have developed rapidly [12].…”