Table 1 Fiber properties of the upstream and downstream side, and coating treatment of each splice point. Abbreviations are SM/PM: Corning PM98 (Core MFD \(6.6(5)~\mu{\mathrm{m}}\), NA unspecified), MMF1: Nufern FUD-4309, Revision: B (Core \(106.5~\mu{\mathrm{m}}\), NA0.2–0.24), MMF2: Nufern 105 Micron Core Power Delivery Fibers (Core \(105(3)~\mu{\mathrm{m}}\), NA0.22(2)), PF: Nufern Precision Matched Passive Polarization Maintaining Large Mode Area Double Clad Fibers (core \(11(1)~\mu{\mathrm{m}}\), NA0.075(5), inner cladding \(125(1)~\mu{\mathrm{m}}\), NA≥0.46), YDF: Nufern Precision Matched Active Polarization Maintaining Large Mode Area Double Clad Fibers (core \(11(1)~\mu{\mathrm{m}}\), NA0.075(5), inner cladding \(125(1)~\mu{\mathrm{m}}\), NA≥0.46), and HPC: OZ Optics PC-04-1060-10/125-P-3.4-18AS-60-X-1-1-HPC collimator

From: Conception, modelling, and characterization of a fiber amplifier with a simple and easy-to-repair configuration intended for the use in harsh environments