K.J. Beales

Drawing-dependent transmission loss in germania-doped silica optical fibres

Abstract Excess attenuation is reported in germania-doped silica glass fibres, especially those optimised for monomode operation at 1.55 μm. This additional loss is found to be dependent on fibre drawing conditions, and possible origins are discussed.

Sensitivity Of The Performance Of Monomode Fibres To The Fabrication Conditions

The effects of fibre drawing tension on the optical properties of various monomode fibre designs is examined. High drawing tensions were found to give low optical loss. Grading the refractive index profile was found to reduce the drawing-induced loss considerably. Fibres with high germania content show the largest drawing effects.

Silicon Oxynitride Coatings To Reduce Mechanical Fatigue And Hydrogen Induced Optical Ageing In Silica Fibres

Monomode silica fibre has been coated during fibre pulling with silicon oxynitride ceramics using an on-line deposition process. The coatings have been tested for their ability to prevent the mechanical and optical ageing of fibre. The ceramic coated fibres are more fatigue resistant than silica having N values of over 100 compared with an N of 25 for silica. rrus ceramic coated fibre need only be proof tested at about half the level required for silica. While silica fibre saturates with hydrogen in 500 hours no hydrogen has been detected in a ceramic coated fibre stored in hydrogen for 1900 hours. This and other experiments at high temperature suggest that silicon oxynitride coatings can prevent the hydrogen content of fibre from reaching unacceptable levels.

Multicomponent glass optical fibres with a lowered water content and reduced loss

Abstract A technique has been developed to reduce the −OH content of multicomponent glasses. The glasses were treated with perfluoropropane and the linear absorption coefficient of −OH reduced from typically 0.08 to as low as 0.01 cm −1 , which corresponds to a reduction of −OH content to approximately 2 ppm. A fibre pulled from treated glasses had a reduced loss at 1.3 μm, and a loss of 2.9 dB km −1 at 1.12 μm which is the lowest reported loss for a fibre prepared by a double crucible technique.