Patent ID: 7305164
Filing Date: 2007-12-04
Classification: B29D,B82Y,C03B,G02B,Y02P

Abstract:
1. A preform for a photonic band-gap optical fibre waveguide, comprising a stack of parallel, elongate primary elements and elongate secondary elements in which, in the transverse cross section, the primary elements have a largest external dimension and groups of primary elements define first interstitial regions, in at least some of which there is or are respectively one or more secondary elements having a largest external dimension which is less than one third of the size of each of the largest external dimensions of the surrounding primary elements, and wherein the arrangement of primary and secondary elongate elements is enclosed, in the transverse cross section, by a large diameter capillary, thereby forming a plurality of outer interstitial regions between an inner periphery of the large diameter capillary and the arrangement of primary and secondary elements.