Double-flame VAD process for high-rate optical preform fabrication

High-rate deposition techniques for the VAD process have been developed by increasing the size of synthesised fine glass particles by means of a new ‘double-flame burner’. VAD core preforms have been increased to 2500 g in size, from which a 580 km-length fibre with 50 μm core diameter can be drawn. A deposition rate of 4.5 g/min from one burner has been attained. Fibres from high-rate deposited preforms exhibit transmission losses of 0.62 dB/km at 1.3 μm and 0.44 dB/km at 1.55 μm.