Abstract: A hollow core optical fibre comprises a tubular jacket; a cladding comprising a plurality of primary capillaries spaced apart from one another in a ring and each bonded to an inner surface of the jacket at a peripheral location around the circumference of the jacket; and a hollow core formed by a central void within the ring of primary capillaries; wherein the cladding further comprises, within each primary capillary, two secondary capillaries and no more, the two secondary capillaries spaced apart from one another and each bonded to an inner surface of the primary capillary at an azimuthal location around the circumference of the primary capillary which is displaced from the peripheral location of the primary capillary.

Abstract: A hollow core photonic bandgap optical fibre comprises: a cladding comprising capillaries in a hexagonal array and a hollow core formed by excluding a hexagonal group of nineteen capillaries from the centre of the hexagonal array. The core is inflated. A core size ratio is 1.26 or above, defined as a ratio of the core diameter to the cladding diameter normalized to the ratio of the core diameter to the cladding diameter in an undistorted hexagonal array; a first ring ratio is between 0.55 and 2.50, defined as a ratio of the length of radially aligned struts separating the capillaries of the first ring to the length of a strut in an undistorted hexagonal array; and a core node spacing is between 0.60 and 1.90, where defined as a ratio of a strut length around the core of a largest corner capillary and a strut length around the core of a smallest side capillary. The fabrication method comprises four different pressures for the core, corner capillary, side capillary and cladding.

Abstract: A hollow core optical fibre comprises a tubular jacket; a cladding comprising a plurality of primary capillaries spaced apart from one another in a ring and each bonded to an inner surface of the jacket at a peripheral location around the circumference of the jacket; and a hollow core formed by a central void within the ring of primary capillaries; wherein the cladding further comprises, within each primary capillary, two secondary capillaries and no more, the two secondary capillaries spaced apart from one another and each bonded to an inner surface of the primary capillary at an azimuthal location around the circumference of the primary capillary which is displaced from the peripheral location of the primary capillary.

Abstract: A hollow core optical fibre comprises a tubular jacket; a cladding comprising a plurality of primary capillaries spaced apart from one another in a ring and each bonded to an inner surface of the jacket at a peripheral location around the circumference of the jacket; and a hollow core formed by a central void within the ring of primary capillaries; wherein the cladding further comprises, within each primary capillary, two secondary capillaries and no more, the two secondary capillaries spaced apart from one another and each bonded to an inner surface of the primary capillary at an azimuthal location around the circumference of the primary capillary which is displaced from the peripheral location of the primary capillary.

Abstract: A preform (10) for an antiresonant hollow core optical fibre comprises an outer jacket tube (12) having an inner surface and a central longitudinal axis (24); a plurality of antiresonant cladding tubes (14) spaced apart at predefined peripheral locations around the inner surface of the outer jacket tube (12), each antiresonant cladding tube (14) in contact with the inner surface such that a central longitudinal axis (26) of each antiresonant cladding tube (14) is at a first radial distance from the central longitudinal axis (24) of the outer jacket tube (12); and a plurality of spacing elements (22) disposed alternately with the antiresonant cladding tubes (14) and each in contact with an outer surface of each of two adjacent antiresonant cladding tubes (14) at one or more contact points (28), the contact points (28) at a second radial distance from the central longitudinal axis (24) of the outer jacket tube (12), the second radial distance being greater than the first radial distance.

Abstract: A hollow core optical fibre comprises a tubular jacket; a cladding comprising a plurality of primary capillaries spaced apart from one another in a ring and each bonded to an inner surface of the jacket at a peripheral location around the circumference of the jacket; and a hollow core formed by a central void within the ring of primary capillaries; wherein the cladding further comprises, within each primary capillary, two secondary capillaries and no more, the two secondary capillaries spaced apart from one another and each bonded to an inner surface of the primary capillary at an azimuthal location around the circumference of the primary capillary which is displaced from the peripheral location of the primary capillary.

Abstract: A hollow core photonic bandgap optical fibre comprises: a cladding comprising capillaries in a hexagonal array and a hollow core formed by excluding a hexagonal group of nineteen capillaries from the centre of the hexagonal array. The core is inflated. A core size ratio is 1.26 or above, defined as a ratio of the core diameter to the cladding diameter normalized to the ratio of the core diameter to the cladding diameter in an undistorted hexagonal array; a first ring ratio is between 0.55 and 2.50, defined as a ratio of the length of radially aligned struts separating the capillaries of the first ring to the length of a strut in an undistorted hexagonal array; and a core node spacing is between 0.60 and 1.90, where defined as a ratio of a strut length around the core of a largest corner capillary and a strut length around the core of a smallest side capillary. The fabrication method comprises four different pressures for the core, corner capillary, side capillary and cladding.

Abstract: A preform (10) for an antiresonant hollow core optical fibre comprises an outer jacket tube (12) having an inner surface and a central longitudinal axis (24); a plurality of antiresonant cladding tubes (14) spaced apart at predefined peripheral locations around the inner surface of the outer jacket tube (12), each antiresonant cladding tube (14) in contact with the inner surface such that a central longitudinal axis (26) of each antiresonant cladding tube (14) is at a first radial distance from the central longitudinal axis (24) of the outer jacket tube (12); and a plurality of spacing elements (22) disposed alternately with the antiresonant cladding tubes (14) and each in contact with an outer surface of each of two adjacent antiresonant cladding tubes (14) at one or more contact points (28), the contact points (28) at a second radial distance from the central longitudinal axis (24) of the outer jacket tube (12), the second radial distance being greater than the first radial distance.