An optical rotary joint includes first and second hollow tubular members. At least one of the first and second hollow tubular members is rotatable about a common longitudinal axis. A ring shaped optical waveguide between the first and second hollow tubular members includes first and second axial faces oriented perpendicular to the common longitudinal axis, an inner circumferential edge facing the outer circumference of the first hollow tubular member, an outer circumferential edge facing the inner circumference of the second hollow tubular member, and a circular light scattering channel formed in the first and/or second axial faces. First optical emitters are arranged to face the outer or inner circumferential edge. Second optical emitters are arranged to face the channel. A first optical receiver is arranged to face the outer or inner circumferential edge. A second optical receiver is arranged to face the channel.

The invention concerns 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 comprises a core extending along the length of said longitudinal axis and a cladding region surrounding the core. At least the cladding region comprises 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 comprises hydrogen and/or deuterium. In at least the degradation resistant length section the PCF further comprises a main coating surrounding the cladding region, which main coating is hermetic for the hydrogen and/or deuterium at a temperature below Th, wherein Th is at least about 50° C., preferably 50° C.<Th<250° C.

The present invention is directed to an optical fiber grating having a core, that is capable of controlling the light signal transmission therethrough by causing at least one of: at least one spectral peak, and/or at least one spectral dip in its core light transmission spectrum, corresponding to at least one predetermined wavelength. The inventive optical fiber diffraction grating comprises at least one longitudinally positioned structural element of a predetermined geometric profile and that is configured for diffracting a portion of the transmitted light signal at at least one predefined wavelength thereof, from at least one core mode into at least one of: at least one cladding mode and/or at least one radiating mode. Various embodiments of a number of novel techniques for fabrication of the inventive optical fiber diffraction grating are provided, inclusive of a novel technique for fabricating the inventive grating from a single material. Advantageously, such novel fabrication techniques rely on configuration of a desired geometric profile for the at least one structural element portion of the novel grating, each profile comprising a number of readily configurable parameters that can be selected and/or adjusted during fabrication, to produce a variety of novel fiber diffraction gratings, each having a corresponding specific desirable core transmission spectrum having at least one of: least one spectral peak, and/or at least one spectral dip therein, corresponding to at least one specific desired wavelength, dependent on the configuration of the applicable geometric profile.

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 non-radial array of microstructure elements provides enhanced wavelength selective filtering. The elements are arranged along a line that does not intersect the center of the core. In this configuration, the first coupling element in an array that is nearest to the core is a non-integer array unit spacing from the main waveguide where the array unit spacing is defined as the flat to flat distance of a hexagonal cell.

An optical rotary joint includes first and second hollow tubular members. At least one of the first and second hollow tubular members is rotatable about a common longitudinal axis. A ring shaped optical waveguide between the first and second hollow tubular members includes first and second axial faces oriented perpendicular to the common longitudinal axis, an inner circumferential edge facing the outer circumference of the first hollow tubular member, an outer circumferential edge facing the inner circumference of the second hollow tubular member, and a circular light scattering channel formed in the first and/or second axial faces. First optical emitters are arranged to face the outer or inner circumferential edge. Second optical emitters are arranged to face the channel. A first optical receiver is arranged to face the outer or inner circumferential edge. A second optical receiver is arranged to face the channel.

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 terahertz polarization beam splitter based on a two-core negative curvature fiber is provided, which relates to the technical field of optical fiber communication. The polarization beam splitter includes: a base circular tube and core separation structures. Multiple large cladding tubes are internally tangent and connected to an inner wall of the base circular tube and arranged at equal intervals along a circumference of the inner wall of the base circular tube, and the multiple large cladding tubes are symmetrically distributed on the inner wall of the base circular tube. Embedded circular tubes are internally tangent and connected to inner walls of the multiple large cladding tubes respectively. The core separation structures are two in number.