ECOC 1975 - ECOC 2013

63
PRACTICAL USE OF MEDIUM LOSS OPTICAL FIBRES
Many of the present prototype and operating systems use some form of
fibre bundle and conventional LED's and detectors. However, the situation
has been changing rapidly recently and fibre bundles of approximately
300 microns diameter are coming into general use. These bundles typically
contain 19 fibres each of 65 microns diameter. Bandwidths of 20 MHz are
easily achieved over 100 metres.
Recent developments in optical connector technology and device packaging
have improved system construction and performance. In particular, device
to bundle coupling has been improved mechanically and in optical
performance by the incorporation of coupling rods or fibres onto the
active device. These coupling rods or fibres are a permanent part of the
device packaging.
The mechanical and environmental properties of fibre bundles are being
improved. The improvements are primarily being achieved through the use
of better sheathing plastics and through improved fibre to fibre
protection within the bundle.
It is likely that, in the future, even medium loss optical fibres will be
used in the form of a cable containing a number of protected individual
fibres. Such cables already exist and their performance in systems has
proved satisfactory. The individual optical fibres have been protected
with a variety of plastic materials without deterioration in the optical
performance. Tensile strengths of several kilograms have been recorded.
ACKNOWLEDGEMENTS
This paper is published with the permission of the Directors of
Pilkington Brothers Limited and Dr. D. S. Oliver, Director of Group
Research and Development.