A New Ge/F−Co-doped SMF with Enhanced SBS Threshold Fabricated by PCVD

A new single-mode fibre (SMF) with high stimulated Brillouin scattering (SBS) threshold which is co-doped with GeO₂ and F₂ in the core is reported. To increase the SBS threshold, the acousto−optic effective area is increased by designing a transverse acoustic waveguide and adjusting the doping level of GeO₂ and F₂ while the designed fiber retains a step optical refractive index profile. The optimal design is found by numerical simulation and the optimal fiber is fabricated by a plasma−activated chemical vapor deposition (PCVD) process. It yields the threshold 6.79 dB, which is higher than the conventional single-mode fiber G.652 and 3dB higher than the Corning® SMF−28e+™ optical fiber with NexCor® technology.