Co-casting and optical characteristics of transparent segmented composite Er:YAG laser ceramics

Abstract

A novel colloidal co-casting process was developed to fabricate laser quality, multisegment composite ceramic laser gain materials. The approach was demonstrated for a three segment transparent composite rod 62 mm long by 3 mm diameter consisting of undoped yttrium aluminus garnet (YAG), 0.25% Er:YAG, and 0.5% Er:YAG. The Er concentration profile in the composite has steep, controllable gradients at the segment interfaces, while maintaining constant dopant concentrations within each segment. The composite rod has 84% transmittance at 1645 nm (the lasing wavelength) with a scatter loss of 0.4% cm−1. Laser operation of such a composite Er:YAG ceramic rod was demonstrated for the first time, with nearly equivalent lasing behavior to an Er:YAG single crystal rod.

The effect of tape casting operational parameters on the quality of adjacently graded ceramic film

“…Kupp et.al. [5] tape cast xylenes-and ethanol-based slurry loaded with particles of micro-and nano-sizes; tapes were fabricated with a casting gap of 0.356 µm and a casting speed of about 70 cm/min. For magnetic cooling thicker films were required [6], so the graded tapes of micro-sized ceramic particles were fabricated from the methylethylketone-based slurry using a gap of a 1000 µm and a casting speed of 20 cm/min.…”

“…In Kupp's et.al. work [5], divider was made of steel and covered the whole tape caster reservoir and the gap under the shearing blade. Authors of magnetic cooling work used a Teflon partition, 1.95 mm wide and covering just the reservoir space, co-flowed slurries were sheared together underneath the blade.…”

“…Another aspect of dividing casting tank into segments is the target to improve alignment of elongated particles into the casting direction, since a torque, generated next to the tank walls, was proven to affect the particles rotation even more than a basic concept of increase in casting speed [5,6]. In comparison of a set of tapered blades installed 5 mm apart from each other at the exit of the tank and array of sharpened pins 0.7 mm from each other, the latter ones shown to exhibit a higher degree of particles orientation in cast tape [8].…”

Synthesis of nanocrystalline yttria powder and fabrication of Cr,Nd:YAG transparent ceramics

“…One is solid-state reactive sintering of oxide powder mixture [12][13][14][15][16][17][18][19][20][21][22]. The other way is vacuum sintering of RE:YAG powders synthesize by wet-chemical method [23][24][25][26][27][28][29].…”

Er:YAG polycrystalline ceramics: The effects of the particle size distribution on the structural and optical properties

“…Er was selected as the dopant ion because of the importance of the Er:YAG active medium for generating laser radiation in the wavelength of 1645 nm and 2940 nm, and the fact that there are only a few reports on the fabrication of Er:YAG polycrystalline ceramics[34][35][36].…”