Vapor-phase Axial Deposition Research Articles

Polarisation characteristics in long length v.a.d. single-mode fibres

Polarisation characteristics in long single-mode fibres are investigated. Single-mode fibres used in the experiment have been fabricated by the v.a.d. (vapour-phase axial deposition) method. It was shown from the measurements on a 21 km single-span v.a.d. fibre that the state of polarisation of the incident light beam can be maintained over a long length when the incident plane of polarisation coincides with the major or minor axis of the single-mode optical fibre.

Transmission properties of 30.4 km v.a.d. fibre

A 30.4 km graded-index fibre has been fabricated by the vapour-phase axial deposition (v.a.d.) method. Optical-time-domain reflectometry was used to characterise the loss uniformity along the longitudinal direction of this fibre. Measured transmission loss and 6 dB bandwidth with good uniformity along this long fibre were 0.54 dB/km and 1200 MHzkm at the 1.3 μm wavelength, respectively.

Materials and processes for fiber preform fabrication—Vapor-phase axial deposition

The vapor-phase axial deposition (VAD) process was developed to realize continuous fabrication of high-silica fiber preforms. This process could be used to fabricate various kinds of optical fibers such as graded-index, single-mode, and high NA fibers. Transmission characteristics of these VAD fibers have improved to the level almost comparable to the best values attained by the MCVD process. The VAD process has excellent prospects as an economical means to produce long-length fibers with good transmission characteristics.

Phosphor-doped silica cladding v.a.d. fibres

Loss reduction of v.a.d. (vapour-phase axial deposition) fibres at wavelengths of 1.3 μm and 1.6 μm was investigated. The infrared absorption loss was reduced by applying SiO2-P2O5 cladding instead of SiO2-B2O3 cladding and by minimising the waveguide imperfection loss. The minimum losses of the fabricated v.a.d. fibre were 0.5 dB/km and 0.28 dB/km at wavelengths of 1.3 μm and 1.6 μm, respectively. This fact indicates that fibres fabricated by the soot process, like those made by the vapour-phase axial-deposition process, can be used as long-wavelength optical transmission media. We have also found the OH absorption abnormality at wavelengths of 0.95, 1.24 and 1.39 μm, and the loss peak values are different from those reported.