nLIGHT Corp. (Vancouver, WA) manufactures its very large mode area (LMA), low numerical aperture (NA), all erbium fibers using proprietary Direct Nanoparticle Deposition (DND) active fiber production technology. Highly doped, LMA erbium fibers are suited for high-power, eye-safe applications at 1.5+ µm such as medical devices.
The new all erbium fibers offer high core absorptions of 60 - 120 dB/m at 1530 nm, low NAs <0.10, cores of 20 - 70 µm and claddings from 125 - 400 micrometers, including LIEKKI Er60-20/125DC, LIEKKI Er60-40/140DC, LIEKKI Er60-60/270DC, LIEKKI Er60-70/400DC, and LIEKKI Er120-20/125DC.
Historically, the fiber laser industry has mainly pursued co-doped erbium-ytterbium (Er-Yb) active fibers as gain medium for higher power eye-safe applications at 1.5+ µm. While such fibers have achieved high powers, the parasitic lasing and amplified spontaneous emission in the ytterbium element are known to limit their performance. Efforts to scale all erbium powers with 980 nm pumping have been limited in efficiency due to erbium fiber limitations, limited brightness pumps and the high quantum defect at 980 nm. These new fibers offer, in combination with nLIGHT's very high-brightness pump diodes at 980 nm and in particular 1470 and 1530 nm, the potential to deliver high powers with slope efficiencies exceeding 45%.
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