An apparatus and method for manufacturing chiral fibers having chiral fiber Bragg gratings properties from UV sensitive optical fibers by using a UV laser beam to impose a chiral modulation of the refractive index at the core of the fiber

Apparatus and method of manufacturing chiral fiber bragg gratings

An optical fiber ( 10 ) made with a central core ( 12 ), a first cladding layer ( 16 ), and a second cladding layer ( 18 ) having a series of perturbations or irregularities formed into the otherwise generally circular outer boundary of the first cladding layer ( 16 ). The irregularities in the first cladding layer ( 16 ) interrupt the propagation of skew rays and encourage coupling into the core ( 12 ).

Optical fiber with irregularities at cladding boundary

Fibre optic cables with improved performance for use in distributed sensing, for instance in distributed acoustic sensors, are disclosed. In one embodiment a fibre optic cable (210) comprises a core (208) and cladding (206) disposed within a buffer material (202) and surrounded by a jacket (204) and arranged so that the core is offset from the centre of the cable. By offsetting the core from the centre of the jacket any bending effects on the core can be maximised compared with the core being located at the centre of the cable.

Optic fibres and fibre optic sensing

A cladding stripper includes a plurality of transversal notches or grooves in the outer surface of an exposed inner cladding of a double clad optical fiber. Position and orientation of the notches can be selected to even out cladding light release along the cladding light stripper, enabling more even temperature distributions due to released cladding light. The notches on the optical fiber can be made with a laser ablation system.

Cladding light stripper and method of manufacturing

Our method of making high bandwidth silica-based multimode optical fiber comprises provision of a non-circular preform, and drawing fiber of chiral structure from the preform. The non-circular preform can be made by maintaining the inside of the tubular preform under reduced pressure during at least part of the collapse, resulting in a non-circular core and cladding. It can also be made by removal (e.g., by grinding or plasma etching) of appropriate portions of the preform, resulting in a circular core and non-circular cladding. In the latter case, fiber is drawn at a relatively high temperature such that, due to surface tension, the cladding assumes substantially circular shape and the core assumes a non-circular shape. The chiral structure is imposed on the fiber in any appropriate way, e.g., by twisting during fiber drawing the fiber alternately in clockwise and couterclockwise sense relative to the preform.

Method of making an improved multimode optical fiber and fiber made by method

An optical fibre having a single mode absorptive core (10) whose position, relative to the cross-sectional plane of the inner multimode cladding (12), varies along the length of the fibre. The periodicity and the magnitude of the relative displacement of the core (10) with respect to the cladding (12) are such that the transfer of radiation from the inner multimode cladding (12) to the core (10) is substantially improved over conventional fibres.

Optical fibre for improved power coupling

A method of making a fiber having a single mode absorptive core whose position relative to the cross sectional plane of the inner multimode cladding varies along the length of the fiber. A groove or grooves are made in the outer cladding of the preform. When fiber is drawn from the grooved preform, the position of the core does not follow the centerline of the fiber; the position within the fiber varies in accordance with the grooves.

Peter Gottfried Berrang

Papers

Optical fibre for improved power coupling

Method including making grooves in a fiber preform which is drawn to create fiber with improved mode coupling due to a resultant wandering of the core