New developments in high power fiber lasers based on alternative materials

Abstract

Sintering of Yb-doped fused silica granulates is a well established technique developed by the IPHT and Heraeus Quarzglas and it produces very homogeneous rare earth doped bulk silica core rods for fiber laser applications. By using a newly developed laser induced deflection (LID) technique we are able to pre-characterize directly the material absorption properties of the bulk material prior to the laser fiber production. The bulk absorption results measured by LID are without scattering effects and they are typically in good agreement with the total attenuation measured in the fibers. We achieved a fiber background loss of 20 dB/km. Furthermore, we present detailed studies of the refractive index homogeneity of the Yb-doped bulk materials and laser fibers to show the unique features of the Yb-doped bulk silica. Multimode double cladding laser fibers with an extra large mode area XLMA fiber design (core diameter up to 100 µm) have been produced from the Yb-doped bulk silica rods by two different techniques. One is a classical jacketing method; the other employs the stacking of un-doped, Yb-and F-doped rods and F-doped tubes. Different fiber types have been tested in different fiber laser setups. The influence of the fiber end cap properties on the fiber laser focus shift is discussed in detail. We have achieved fiber laser output powers up to 1.925 kW, limited only by the pump power. We also investigated the long term laser stability at different power levels.

Metal clad active fibres for power scaling and thermal management at kW power levels

“…This fibre design consisted of a powder sintered fused silica core material [19,20] co-doped with approximately 0.04 wt% Yb 2 O 3 and 0.8 wt% Al 2 O 3 . The inner cladding of this fibre was pure fused silica (F300) and shaped octagonal for increased pump absorption and finally overclad with a down doped fluorosilicate layer to enable pump guidance.…”

Blue and near-infrared up-conversion in double-air-cladding Tm3+-doped silica fiber under 1064 nm excitation

“…At present, most of Tm 3? doped fibers is fabricated by using the chemical vapor deposition method and the solution doping method, and it is difficult to obtain the large-diameter fiber core (Renner-Erny et al 2007;Langner et al 2011).…”

Fabrication and laser performance of Yb3+/Al3+ co-doped photonic crystal fiber synthesized by plasma nonchemical vapor deposition method

“…In recent years, the high-power fiber lasers [1][2][3] such as Yb-doped fiber lasers [4][5][6] have already achieved multi-kilowatt cw outputs by obtaining the ultra-large active core-area to suppress nonlinear effects [7,8]. At present, most of available RE-doped fibers are fabricated by the combination of modified chemical vapor deposition (MCVD) and solution doping.…”