A robust, large air fill fraction holey fibre

Summary form only given. Holey fibres have an array of holes around the core which run along the entire length of the fibre. This reduces the effective index of the cladding and provides the light guiding mechanism. This new type of fibre offers a wide range of unique optical properties which make them of great interest for a wide range of applications including telecommunications and sensing. We report the fabrication of externally-clad holey fibre produced in a two stage drawing process. A borosilicate glass outer cladding was added to a conventional silica capillary stack containing 55 capillaries and that had been pre-drawn to appropriate dimensions. The resulting composite structure was then pulled into a glass-clad holey fibre of /spl sime/250 pm outer diameter, and coated with conventional polymer coating. The additional strength provided by the two coatings allowed longer lengths of fibre to be produced, with larger air holes than previously possible, and made the fibre easy to handle. To date /spl ges/50 m lengths have been produced, but kilometre lengths could be produced without modifying the procedure. We believe this to be a significant step in the development of truly useful and practical holey fibre structures.