Optical-fibre-communication systems have been demonstrated over realistic section lengths in a number of laboratories around the world, and the basic components developed to the stage where quantity production at reasonable cost seems a viable proposition. One of the major problems in transferring these systems from the laboratory to the field is that of connecting the various parts together. Device active areas and fibre cores are very small, usually less than 100μm in diameter, and, to be efficient, connections have to be made with great precision