Described are systems and techniques for characterizing optical fibers. Disclosed systems and techniques employ optical metrology, functional metrology, or both to characterize microstructured optical fibers and determine fiber characteristics, errors, and quality control metrics. The characteristics, errors, and quality control metrics are useful for improving the manufacturing of optical fibers.

A technique for fabricating a hollow core optical fiber with a controllable core region (in terms of diameter) is based upon regulating conditions (gas flow, volume, and/or temperature) within the hollow core region during the fiber draw process. The introduction of a gas, or any change in volume or temperature of the hollow core region, allows for the diameter of the hollow core region to self-regulate as a multistructured core rod (MCR) is drawn down into the final hollow core optical fiber structure. This self-regulation provides a core region having a diameter that selected and then stabilized for the duration of the draw process. The inventive process is also useful in controlling the diameter of any selected hollow region of an MCR including, but not limited to, shunts and corner capillaries disposed around the core region.

An optical fiber, manufacturing intermediate for forming an optical fiber and a method for forming an optical fiber. The method includes providing a manufacturing intermediate having an elongate body and having an aperture extending through the elongate body along an axial dimension of the elongate body, a boundary of the aperture defining an internal surface of the manufacturing intermediate. The method further includes etching the internal surface of the manufacturing intermediate using an etching substance, and drawing the manufacturing intermediate along the axial dimension so as to form the optical fiber.

A shaped tube (50,51) for use as a component in the fabrication of an antiresonant hollow core optical fibre, the shaped tube having a side wall with a transverse cross-sectional shape comprising a number of major curved portions (52) alternating with the same number of minor substantially straight portions (54), each curved portion (52) having an inwardly curving shape, and each straight portion (54) being equidistant from a central longitudinal axis of the shaped tube (50,51).

A cylindrical electrode module of a fiber optic laser system includes an inner cylinder having an inner repeating pattern of longitudinally-aligned positive and negative electrodes on an outer surface of the inner cylinder. The cylindrical electrode mode includes an outer cylinder that encloses the inner cylinder. The outer cylinder that has an outer repeating pattern of longitudinally-aligned negative and positive electrodes on an inner surface of the inner cylinder that are in corresponding and complementary, parallel alignment with the positive and negative electrodes of the inner repeating pattern on the outer surface of the inner cylinder. The cylindrical electrode module includes an optical fiber having an input end configured to align with and be optically coupled to a pump laser. The optical fiber is wrapped around the inner cylinder within the outer cylinder to form a cylindrical fiber assembly. The electrodes are activated to achieve quasi-phase matching.

A hollow core photonic crystal fiber (PCF) including an outer cladding region and seven hollow tubes surrounded by the outer cladding region. Each of the hollow tubes is fused to the outer cladding to form a ring defining an inner cladding region and a hollow core region surrounded by the inner cladding region. The hollow tubes are not touching each other but are arranged with distance to adjacent hollow tubes. The hollow tubes each have an average outer diameter d2 and an average inner diameter d1, wherein d1/d2 is equal to or larger than about 0.8, such as equal to or larger than about 0.85, such as equal to or larger than about 0.9. Also, a laser system.

A method for manufacturing an optical fibre, in which a preform is inserted into a furnace; the preform is drawn via an outlet of the furnace; and the drawn preform has a working area including a structure composed of walls, and gas streams are applied to the two opposite faces of these walls, which streams run along the walls in opposite directions, so as to subject the walls to a shear force of gas streams counter-propagating on either side of the walls. A device for manufacturing an optical fibre is also provided.

A method for manufacturing a capillary usable as part of a hollow-core photonic crystal fiber. The method includes obtaining a capillary having capillary wall including a first wall thickness; and chemically etching the capillary wall to reduce the wall thickness of the capillary wall. During performance of the etching, a control parameter is locally varied along the length of the capillary, the control parameter relating to reactivity of an etchant used in the etching, so as to control the etched wall thickness of the capillary wall along the capillary length. Also disclosed is a capillary manufactured by such a method and various devices including such a capillary.

A hollow-core anti-resonant-reflecting fibre (HC-AF) includes a hollow-core region, an inner cladding region, and an outer cladding region. The hollow-core region axially extends along the HC-AF. The inner cladding region includes a plurality of anti-resonant elements (AREs) and surrounds the hollow-core region. The outer cladding region surrounds the inner cladding region. The hollow-core region and the plurality of AREs are configured to provide phase matching of higher order hollow-core modes and ARE modes in a broadband wavelength range.

A hollow-core anti-resonant-reflecting fibre (HC-AF) includes a hollow-core region, an inner cladding region, and an outer cladding region. The hollow-core region axially extends along the HC-AF. The inner cladding region includes a plurality of anti-resonant elements (AREs) and surrounds the hollow-core region. The outer cladding region surrounds the inner cladding region. The hollow-core region and the plurality of AREs are configured to provide phase matching of higher order hollow-core modes and ARE modes in a broadband wavelength range.