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La 2 O 3 ‐Al 2 O 3 ‐SiO 2 Glasses for High‐Power, Yb 3+ ‐Doped, 980‐nm Fiber Lasers
Author(s) -
Dejneka Matthew J.,
Hanson Benjamin Z.,
Crigler Steve G.,
Zenteno Luis A.,
Minelly John D.,
Allan Douglas C.,
Miller William J.,
Kuksenkov Dmitri
Publication year - 2002
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.2002.tb00229.x
Subject(s) - materials science , fiber laser , numerical aperture , laser , multi mode optical fiber , cladding (metalworking) , fiber , optics , optoelectronics , plastic clad silica fiber , fabrication , doping , hard clad silica optical fiber , optical fiber , dispersion shifted fiber , wavelength , fiber optic sensor , medicine , physics , composite material , metallurgy , alternative medicine , pathology
Single‐mode semiconductor pumps have failed to keep pace with the increasing power requirements of Er‐doped fiber amplifiers (EDFAs), so there is a need for high‐powered 980‐nm sources. Yb 3+ ‐doped tapered fiber lasers can provide high‐power output by conversion of a low‐brightness, high‐powered, 920‐nm, multimode broad stripe laser diode to a high‐brightness, 980‐nm, single‐mode output. The tapered fiber laser requires a fiber with high numerical aperture (NA) (>0.4), a rectangular core, and good Yb 3+ spectroscopy for efficient operation. CVD‐based fiber fabrication methods are incapable of delivering fibers with an NA > ∼0.3 or with good efficiency at 980 nm so a new method of high‐NA fiber fabrication was developed. The core glass composition is critical for maintaining a high‐NA fiber with good power extraction while avoiding phase separation, loss, and clustering. The SiO 2 level controlled the NA and interdiffusion between core and clad, while the Al 2 O 3 /La 2 O 3 ratio controlled phase separation. A La 2 O 3 ‐Al 2 O 3 ‐SiO 2 glass was developed that is compatible with a pure SiO 2 cladding glass and has a laser slope efficiency of 70% at 980 nm. The optimized fiber composition yielded 450 mW of 980‐nm power in a single‐mode fiber.