An optical fibre for an ultrafast laser endoscope including at least the following structures: a hollow core, the periphery of which has an order of symmetry of at least six when considering axes of symmetry passing through the centre of the core and through the centre of convex shapes, seen from the centre of the core, the convex shapes at least partly making up the periphery of the core; an intermediate layer of cellular structure surrounding the core; a light conducting peripheral structure surrounding the intermediate layer of cellular structure; and an outer sheath surrounding the light-conducting peripheral structure. A particular advantage of the optical fibre is that it optimizes the emission of a high-power flux associated with fluorescence collection.

An optical fiber, an apparatus for receiving input radiation and broadening a frequency range, a radiation source, a metrology arrangement and a lithographic apparatus are provided. The optical fiber comprises a hollow core, a cladding portion and a support portion. The cladding portion surrounds the hollow core and comprises a plurality of anti-resonance elements for guiding radiation through the hollow core. The support portion surrounds and supports the cladding portion and comprises an inner support portion, an outer support portion and a deformable connecting portion that connects the inner support portion to the outer support portion.

A method of fabricating a hollow-core photonic-bandgap fiber, comprising the steps of: providing a stack of capillaries, wherein the stack has a hollow core and the capillaries at a boundary of the core comprise a plurality of first, corner core capillaries and a plurality of second, intermediate core capillaries; applying a pressure differential between the corner core capillaries and the intermediate core capillaries, whereby a size of the corner core capillaries can be controlled in relation to the intermediate core capillaries; and reducing the stack to a fiber, wherein the fiber has a hollow core and a cladding which surrounds the core at a core boundary and comprises a lattice or network of struts and interstitial nodes which together define an array of cavities.

A device for connecting a fiber preform including a plurality of elongate holes extending substantially parallel to a longitudinal axis of the fiber preform to a pressure supply system, the device including a first surface to be connected to an end face of the fiber preform where the plurality of elongate holes end, a second surface including at least two ports configured to be in fluid connection with the pressure supply system, and a channel system within the device connecting the plurality of elongate holes at the first surface to the at least two ports, wherein a density of the at least two ports at the second surface is smaller than a density of the plurality of corresponding elongate holes at the first surface.

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.

Optical components and methods of manufacture thereof. A first optical component has a hollow-core photonic crystal fiber includes internal capillaries for guiding radiation and an outer capillary sheathing the internal capillaries; and at least an output end section having a larger inner cross-sectional dimension over at least a portion of the output end section than an inner cross-sectional dimension of the outer capillary along a central portion of the hollow-core photonic crystal fiber prior to the output end section. A second optical component includes a hollow-core photonic crystal fiber and a sleeve arrangement.

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 Photonic Crystal Fiber (PCF) a method of its production and a supercontinuum light source comprising such PCF. The PCF has a longitudinal axis and includes a core extending along the length of said longitudinal axis and a cladding region surrounding the core. At least the cladding region includes a plurality of microstructures in the form of inclusions extending along the longitudinal axis of the PCF in at least a microstructured length section. In at least a degradation resistant length section of the microstructured length section the PCF includes hydrogen and/or deuterium. In at least the degradation resistant length section the PCF further includes a main coating surrounding the cladding region, which main coating is hermetic for the hydrogen and/or deuterium at a temperature below T.sub.h, wherein T.sub.h is at least about 50 C., preferably 50 C.<T.sub.h<250 C.

A fiber laser system includes a high power pump laser, an optical fiber that is aligned to receive output from the high power pump laser. The fiber laser system includes a first pair of orthogonally opposed, periodic electrode structures longitudinally aligned on opposite first and second sides of the optical fiber. The fiber laser system includes a controller that is communicatively coupled to the first pair of periodic electrode structures. The controller performs variable period poling of the first pair of periodic electrode structures to achieve quasi-phase matching (QPM).

According to embodiments of the present invention, a fiber preform or an optical fiber is provided. The fiber preform or the optical fiber includes a core region having a plurality of cores, wherein two cores of the plurality of cores are bridged by an air gap, and a cladding arrangement including a first cladding region having a plurality of structures surrounding the core region, and a second cladding region in between the core region and the first cladding region, the second cladding region having a plurality of tubes, wherein at least one split is defined in the second cladding region. According to further embodiments of the present invention, a method for forming the fiber preform, a method for forming the optical fiber, an optical coupler having the optical fiber, an optical combiner having the optical fiber, and an optical apparatus having the optical fiber are also provided.