nLight has released its very large mode area (LMA), low numerical aperture (NA), all erbium fibers manufactured using its Direct Nanoparticle Deposition (DND) active fibre production technology.
Highly doped, LMA erbium fibres are ideal for high-power, eye-safe applications at 1.5+ µm such as LIDAR, range finding, sensing, medical and even directed energy applications.
The new all erbium fibres offer high core absorptions of 60 to 120dB/m at 1,530nm, low NAs <0.10, cores of 20 to 70µm and claddings from 125 to 400µm, including Liekki Er60-20/125DC, Liekki Er60-40/140DC, Liekki Er60-60/270DC, Liekki Er60-70/400DC, and Liekki Er120-20/125DC.
Historically, the fibre laser industry has mainly pursued co-doped erbium-ytterbium (Er-Yb) active fibres as gain medium for higher power eye-safe applications at 1.5+µm. While such fibres 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 980nm pumping have been limited in efficiency due to erbium fibre limitations, limited brightness pumps and the high quantum defect at 980nm.
These new fibres offer in combination with nLight's very high-brightness pump diodes at 980nm and in particular 1,470 and 1,530nm the potential to deliver high powers with slope efficiencies exceeding 45 per cent.