Antiresonant hollow core preforms and optical fibres and methods of fabrication

摘要

A preform for an antiresonant hollow core optical fibre with an outer jacket tube 12 having an inner surface and a central longitudinal axis; with a plurality of antiresonant cladding tubes 14 or capillaries spaced apart at predefined peripheral locations around the inner surface of the outer jacket tube, each antiresonant cladding tube in contact with the inner surface; and with a plurality of spacing elements 22 disposed alternately with the tubes. The spacing elements may be further out towards the outer jacket tube at a predefined ratio. The spacing elements may be solid or hollow. The spacing element may comprise spacing sub-elements (22, fig 9) and may be of different shapes (22, fig 10), and the antiresonant tubes may contain one or more further antiresonant tubes within (fig 12), and the structures and sizes may be constant. The fibre is made (fig 5, fig 15) with the spacing features designed to ensure the product has a structure with distances suitable to avoid interactions between the antiresonant tubes by overcoming the tendency for tubes to move and rotate away from the ideal arrangement, so that optical loss is low.