Fluorine doping in the consolidation process of VAD soot preform for single-mode fibers

Advantages of depressed cladding single-mode fibers have been recognized for a couple of years, and many studies of these fibers by the MCVD method have been published. However, only a few studies have been reported on the VAD method.1,2 We now report a new simple technique for fabrication of depressed cladding single-mode fibers by the VAD method with low losses such as 0.40 dB/km at 1.30 μm and 0.28 dB/km at 1.55 μm.