Hollow core optical fiber and method of making the same

A method of fabricating a microstructured core rod for a hollow core photonic bandgap optical fiber, comprising:

• a) arranging a stack of capillary tubes in an initial lattice configuration including a central hollow area of a predetermined diameter d;
• b) placing an over-sized core tube in the central hollow area, the over-sized core tube having a diameter d+Δd such that a set of capillary tubes surrounding the over-sized core tube re-position closer together than the initial lattice configuration;
• and
• c) drawing the arrangement formed in step b) into the microstructured core rod with the over-sized core tube forming a core wall comprising essentially uniformly spaced-apart nodes with substantially uniform length struts formed therebetween to prevent propagation of surface modes along the core wall.

A method of fabricating a microstructured core rod for a hollow core photonic bandgap optical fiber, comprising the steps of:

• a) arranging a stack of capillary tubes in an initial lattice configuration including a central hollow area of a predetermined diameter d, the stack of capillary tubes including a first set of capillary tubes with a first diameter d1 positioned immediately adjacent to the central hollow area and a second set of capillary tubes with a second diameter d2>d1 positioned at remaining locations to form the initial lattice configuration;
• b) placing a core tube in the central hollow area, wherein the first set of capillary tubes are disposed in a close-packed formation with the core tube, exhibiting minimal interstitial spacing therebetween;
• and
• c) drawing the assembly formed in step b) into the microstructured core rod with the core tube forming a core wall comprising uniformly spaced-apart nodes with uniform length struts formed therebetween.

A method of fabricating a microstructured core rod for a hollow core photonic bandgap optical fiber, comprising:

• arranging a stack of capillary tubes in an initial lattice configuration including a central hollow area of a predetermined diameter d, the stack of capillary tubes including a set of non-circular capillary tubes positioned immediately adjacent to the central hollow area and a set of circular capillary tubes positioned at remaining locations to form the initial lattice configuration;
• placing a core tube in the central hollow area, wherein the set of non-circular capillary tubes are disposed in a close-packed formation with the core tube, exhibiting minimal interstitial spacing therebetween;
• and
• drawing the close-packed lattice into the microstructured core rod with the core tube forming a core wall comprising uniformly spaced-apart nodes with uniform length struts formed therebetween.