Processing Developments Towards a Polycrystalline YAG Fiber Laser (Preprint)

• Main Authors: Kim,Hyunjun, Hay,Randall S, McDaniel,Sean A, Cook,Gary, Usechak,Nicholas G, Urbas,Augustine M, Shugart,Kathleen N, Lee,HeeDong, Kadhim,Ali H, Brown,Dean P, Griffin,Benjamin, Fair,Geoff E, Corns,Randall G, Potticary,Santeri A, Hopkins,Frank K, Averett,Kent L, Zelmon,David E, Parthasarathy,Triplicane A, Keller,Kristin A
• Format: Report
• Language: English

Polycrystalline Yttrium Aluminum Garnet (YAG) in fiber form is a promising candidate as a laser host for high energy laser generation. However the stringent optical properties demanded by this application necessitates processing a nearly defect free fiber that is the order of ten microns in diameter. Despite 2 decades of processing research, the processing of such a fiber has eluded scientists. Tensile tests on polycrystalline YAG fibers provided valuable information about the sources and locations of the defects. Using this information, processes were modified to reduce the size and population of defects. Key defect sources include powder agglomerates, aggregates, ball-milling contaminants, and fugitive organic contaminants. They were removed by powder classification using centrifugations and filtrations. 2nd phase inclusions were observed and its sources were identified as silica from the alumina tube used for low temperature sintering and non-stoichiometry generated by powder centrifugations. Another defect is the surface roughness and it significantly scatters light from the fiber. Journal of the American Ceramic Society , 01 Jan 0001, 01 Jan 0001,