Towards monomode proportioned fibreoptic preforms by extrusion

Extrusion of inorganic glass melts is demonstrated as a helpful approach fo r making fibreoptic preforms. Thus rods, and fine bore tubes, of good dimen sional control and surface finish have been made of sodium borosilicate gla sses and gallium lanthanum sulphide glasses. Problems of material compatibi lity and design of the extruder die have been addressed. One-step extrusion of core/clad preforms is also demonstrated, and optimisation of the extrud er die design described to minimise taper of the core/clad ratio within the constant outside diameter preform. (C) 1999 Elsevier Science B.V. All righ ts reserved.