20 February 2007 Diode-bar side pumping of double-clad fibers
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We demonstrate direct diode-bar side pumping of a Yb-doped fiber laser using embedded-mirror side pumping (EMSP). In this method, the pump beam is launched by reflection from a micro-mirror embedded in a channel polished into the inner cladding of a double-clad fiber (DCF). The amplifier employed an unformatted, non-lensed, ten-emitter diode bar (20 W) and glass-clad, polarization-maintaining, large-mode-area fiber. Measurements with passive fiber showed that the coupling efficiency of the raw diode-bar output into the DCF (ten launch sites) was ~84%; for comparison, the net coupling efficiency using a conventional, formatted, fiber-coupled diode bar is typically 50-70%, i.e., EMSP results in a factor of 2-3 less wasted pump power. The slope efficiency of the side-pumped fiber laser was ~80% with respect to launched pump power and 24% with respect to electrical power consumption of the diode bar; at a fiber-laser output power of 7.5 W, the EMSP diode bar consumed 41 W of electrical power (18% electrical-to-optical efficiency). When end pumped using a formatted diode bar, the fiber laser consumed 96 W at 7.5 W output power, a factor of 2.3 less efficient, and the electrical-to-optical slope efficiency was lower by a factor of 2.0. Passive-fiber measurements showed that the EMSP alignment sensitivity is nearly identical for a single emitter as for the ten-emitter bar. EMSP is the only method capable of directly launching the unformatted output of a diode bar directly into DCF (including glass-clad DCF), enabling fabrication of low-cost, simple, and compact, diode-bar-pumped fiber lasers and amplifiers.
© (2007) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Sean W. Moore, Sean W. Moore, Jeffrey P. Koplow, Jeffrey P. Koplow, Andrea Hansen, Andrea Hansen, Georg Wien, Georg Wien, Dahv A. V. Kliner, Dahv A. V. Kliner, "Diode-bar side pumping of double-clad fibers", Proc. SPIE 6453, Fiber Lasers IV: Technology, Systems, and Applications, 64530K (20 February 2007); doi: 10.1117/12.702015; https://doi.org/10.1117/12.702015


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