Containerless laser melt process

In summary, continuous sapphire fibers are commercially available, and new YAG fibers are readily achieved with the Saphikon process, or the LHPG process (see Chapter 6), or else by the new containerless laser melt process (Chapter 4). Currently however, there is only one route known, i.e., HP-LCVD, that might eventually be capable of yielding continuous, single crystal fibers such as SiC or titanium carbide fibers. A single crystal SiC fiber by LCVD has... 

One inviscid melt spinning process, the containerless laser heated melt process (Chapter 4.4.4) is believed to facilitate the formation of fibers by increasing the viscosity of the inviscid melt (and jet lifetime) at a normal quench rate of IC K/s, i.e., without increasing the quench rate to -10 K/s. 

Figure 13. Containerless laser-heated melt process. Redrawn from J. K. Weber, J. J. Felton, B. Cho and P. C. Nordine, Glass fibres of pure and erbium- or neodymium-doped yttria-alumina compositions. Nature, 393,769-771 (1998).

The economics and scalability of the new process are not known. The materials cost and the cost of operating a laser process are probably about the same for an amorphous YAG sensor fiber made by the containerless laser heated melt process and a for single crystal YAG sensor fiber made by laser heated pedestal growth (Chapter 4.5.2). And both are containerless processes. However the higher process speed may favor the laser heated melt process (1.5 m/s) over the laser heated pedestal process (1 mm/s). 

Three processes are known to fabricate continuous yttrium aluminum garnet (YAG) fibers. Single crystal YAG fibers are obtained by the edge defined film fed growth process and by the laser heated float zone process (Chapter 4.5). Both are slow processes. Amorphous YAG glass fibers have recently been demonstrated by a containerless laser heated melt process (Chapter 4.4). Polycrystalllne YAG fibers can be obtained with sol-gel and related processes (this chapter). These are potentially fast processes. 

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