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 resonant fiber optic gyroscope (RFOG) comprises two integrated photonics interfaces coupling the optical resonator coil to the multi-frequency laser source that drives the RFOG; wherein the two integrated photonics interfaces comprise a first waveguide layer and a second waveguide layer wherein the first waveguide layer comprises two waveguide branches which come together to form a single waveguide branch; the second waveguide layer comprises two waveguide branches which remain separate from each other; and wherein the waveguide structure is configured to match an integrated photonics mode to a fiber mode supported by an optical fiber.

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 multi-core optical fibre comprises a plurality of cores embedded in cladding. The cladding comprises a polymer. The cladding has an outer cross-sectional shape with an order of rotational symmetry of less than or equal to 4. By limiting the rotational symmetry of the multi-core optical fibre, rotational alignment of the cores with light sources/light detectors may be made easier. Also provided are optical cables and kits including the multi-core optical fibre, and a method of fabricating a multi-core polymer optical fibre.

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 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 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 Th is at least about 50° C., preferably 50° C.<Th.sub.h<250° C.

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 field of waveguides is disclosed. A tubular electromagnetic waveguide includes a hollow central portion defined by a first set of at least seven primary hollow tubes that are distributed annually about the hollow central portion, and a second set of tubes including at least one secondary hollow tube; when there are a plurality thereof positioned annularly around the primary hollow tubes the area of the at least one secondary hollow tube is comprised between 0.35 and 0.50 times the area of the hollow central portion. The hollow tubes of the first set are substantially of same size and distant from one another.

An optical waveguide is formed on a support member. A second cladding layer is formed on a surface of a first cladding layer so as to cover a core layer. An opening is opened at the second cladding layer-side, penetrates the second cladding layer and the core layer, and closed at the first cladding layer-side. The opening has a first surface and a second surface ranging from the opened side to the closed side. In a vertical section taken along a longitudinal direction of the core layer, a first angle between a perpendicular line drawn from an opening end of the first surface to the surface of the first cladding layer and the first surface, and a second angle between a perpendicular line drawn from an opening end of the second surface to the surface of the first cladding layer and the second surface are all acute angles.