US 7,321,712 B2
Optical waveguide
David Philip Williams, Bath (United Kingdom); Timothy Adam Birks, Bath (United Kingdom); Philip St. John Russell, Bath (United Kingdom); Peter John Roberts, Bath (United Kingdom); Hendrik Sabert, Stelle (Germany); and Alexander Onischenko, Surrey (United Kingdom)
Assigned to Crystal Fibre A/S, Birkerod (Denmark)
Filed on Jun. 20, 2005, as Appl. No. 11/155,648.
Application 11/155648 is a continuation in part of application No. PCT/GB2004/001288, filed on Mar. 22, 2004.
Application PCT/GB2004/001288 is a continuation in part of application No. PCT/GB03/05591, filed on Dec. 22, 2003.
Claims priority of application No. 0229826.3 (GB), filed on Dec. 20, 2002; application No. 0302632.5 (GB), filed on Feb. 05, 2003; application No. 0306593.5 (GB), filed on Mar. 21, 2003; application No. 0306606.5 (GB), filed on Mar. 21, 2003; application No. 0314485.4 (GB), filed on Jun. 20, 2003; application No. 0321991.2 (GB), filed on Sep. 19, 2003; application No. 0322024.1 (GB), filed on Sep. 19, 2003; and application No. 0413843.4 (GB), filed on Jun. 21, 2004.
Prior Publication US 2005/0276556 A1, Dec. 15, 2005
Int. Cl. G02B 6/02 (2006.01); G02B 6/20 (2006.01); G02B 6/16 (2006.01)
U.S. Cl. 385—125  [385/122; 385/123; 385/146] 32 Claims
OG exemplary drawing
 
1. An elongate waveguide for guiding light comprising:
a core comprising an elongate region of relatively low refractive index;
a microstructured region around the core comprising elongate regions of relatively low refractive index interspersed with elongate regions of relatively high refractive index, said microstructured region comprising a photonic band-gap structure; and
a boundary at the interface between the core and the microstructured region, said boundary region has a shape such that, in use, light guided by the waveguide is guided in a transverse mode in which, in the transverse cross-section, more than 95% of the guided light is in the regions of relatively low refractive index in the waveguide and such that the light is guided in a transverse mode providing an F-factor of less than 0.7 Λ−1, the boundary comprising, in the transverse cross-section, a region of relatively high refractive index, which is connected to the microstructured region at a plurality of nodes, at least one relatively enlarged region around the boundary; and
wherein the boundary fulfills at least one of the conditions selected from the group consisting of a) the boundary has twelve nodes and at least one enlarged region substantially at a mid-point between a pair of relatively less-widely-spaced apart neighboring nodes,
b) the boundary has less than six enlarged regions substantially at a mid-point between six pairs of relatively more-widely-spaced apart neighboring nodes or more than six enlarged regions substantially at a mid-point between six pairs of relatively more-widely-spaced apart neighboring nodes, and
c) the boundary has less than twelve nodes or more than twelve nodes.