Embodiments involve optical waveguides with spongy material for cladding or layers that include compressible gas pockets. The refractive index of the porous cladding material will change when compressed, bent, or stretched. Measurements for pressure, strain, bending, etc., may be obtained by monitoring the signal degradation and/or escape of radiant energy, e.g., IR, etc., from the core and out through the spongy cladding, where it may be picked up by a neighboring core. Optical waveguides configured as fibers may be easily sewn to stretchable materials, such as athletic tape, fabrics used in umbrellas, balloons, fabrics used in clothing, etc., to meet a robust number of applications.

A delivery fiber assembly suitable for delivering broad band light and including a delivery fiber and a connector member. The delivery fiber has a length, an input end for launching light, and a delivery end. The delivery fiber includes along its length a core region and a cladding region surrounding the core region, the cladding region includes a cladding background material having a refractive index N.sub.bg and a plurality of microstructures in the form of inclusions of solid material having refractive index up to N.sub.inc and extending in the length of the longitudinal axis of the delivery fiber, wherein N.sub.inc<N.sub.bg. The plurality of inclusions in the cladding region is arranged in a cross-sectional pattern including at least two rings of inclusions surrounding the core region. The connector member is mounted to the delivery fiber at a delivery end section of the delivery fiber including the delivery end.

A microstructured optical fiber having a length and a longitudinal axis along its length, the finer including a core region capable of guiding light along the longitudinal axis and a cladding region which surrounds the core region, the cladding region comprising a cladding background material and a plurality of cladding features within the cladding background material, the cladding features being arranged around the core region, wherein the cladding region comprises an inner cladding region comprising an innermost ring of cladding features and an outer cladding region comprises outer cladding rings of outer cladding features, the innermost ring consisting of those cladding features being closest to the core region, wherein the rings of cladding features each comprise bridges of cladding background material separating adjacent features of the ring, wherein the bridges of the innermost ring have an average minimum width (w1), the minimum width of a bridge of a ring being the shortest distance between two adjacent features of the ring; and wherein at least one outer cladding ring has an average minimum width (w2) of bridges that is larger than the average minimum width (w1) of the bridges of the innermost ring. Also described are a cascade optical fiber with at least one fiber as described, as well as a source of supercontinuum radiation.

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.

A broadband light source device for creating broadband light pulses includes a hollow-core fiber and a pump laser source device. The hollow-core fiber is configured to create the broadband light pulses by an optical non-linear broadening of pump laser pulses. The hollow-core fiber includes a filling gas, an axial hollow light guiding fiber core configured to support core modes of a guided light field, and an inner fiber structure surrounding the fiber core and configured to support transverse wall modes of the guided light field. The pump laser source device is configured to create and provide the pump laser pulses at an input side of the hollow-core fiber. The transverse wall modes include a fundamental transverse wall mode and second and higher order transverse wall modes.

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.

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.

An anti-resonant hollow-core fiber comprising a first tubular, cladding element which defines an internal cladding surface, a plurality of second tubular elements which are attached to the cladding surface and together define a core with an effective radius, the second tubular elements being arranged in spaced relation and adjacent ones of the second tubular elements having a spacing therebetween, and a plurality of third tubular elements, each nested within a respective one of the second tubular elements.