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.

This disclosure provides a waveguide including a sequence of variable transparency segments, wherein each variable transparency segment of the sequence of variable transparency segments is configured to vary its transparency by the electromagnetically Induced Transparency (EIT) effect and further vary its transparency in response to an incident electromagnetic field; and a plurality of separator segments interspersed within the sequence of variable transparency segments so that each variable transparency segment: has a first separation distance from a first other variable transparency segment being a first predetermined number of variable transparency segments preceding or succeeding in the sequence of variable transparency segments, has a second separation distance from a second other variable transparency segment being a second predetermined number of variable transparency segments preceding or succeeding in the sequence of variable transparency segments, and is uniquely identified by a combination of separation distances comprising its first and second separation distances.

A waveguide including: a first section, the first section configured to generate, by a non-linear optical process, a broadened wavelength spectrum of pulsed radiation provided to an input end of the waveguide; a second section, the second section including an output end of the waveguide, the second section configured to exhibit a larger absolute value of group velocity dispersion than the first section; wherein a length of the second section is configured to reduce a peak intensity of one or more peaks in the broadened wavelength spectrum by at least 20%.

A terminated hollow-core optical fiber includes a capillary, a hollow-core optical fiber including a structured cladding, and an endcap. A first end of the hollow-core optical fiber terminates inside the capillary a non-zero distance away from a first end face of the capillary. The hollow-core optical fiber is adhered to the capillary at a second end face of the capillary where the hollow-core optical fiber extends out of the capillary. The endcap is fused to the first end face of the capillary. The endcap has a larger diameter than the first end of the hollow-core optical fiber. This termination scheme does not require fusing the hollow-core fiber itself to the endcap or any other part. Therefore, this termination scheme is applicable to hollow-core fibers with a structured cladding that cannot tolerate the temperatures associated with fusing the hollow-core fiber to another part.

An IR-transmitting glass fiber configured to include a holey-microstructured core and a cladding surrounding the core. Glass material used at least in the core is one of the heavy metal oxide glasses, where the glass network former is an oxide selected from GeO.sub.2, TeO.sub.2, Sb.sub.2O.sub.3, and Bi.sub.2O.sub.3, while each and every component of the fiber includes only an oxide glass material and is devoid of any other materials.

An apparatus (100) for receiving input radiation (108) and broadening a frequency range of the input radiation so as to provide broadband output radiation (110). The apparatus comprises a fiber (102), wherein the fiber (102) may comprise a hollow core (104) for guiding radiation propagating through the fiber (102). The apparatus (100) further comprises an apparatus for providing a gas mixture (106) within the hollow core (104). The gas mixture (106) comprises a hydrogen component, and a working component, wherein the working component is for broadening a frequency range of a received input radiation (108) so as to provide the broadband output radiation (110). The apparatus may be included in a radiation source.

The present invention provides a gas measuring method based on photothermal effect in hollow-core optical fiber comprising: filling a target gas into the core of a hollow-core optical fiber; coupling a probe light and a periodically modulated pump light into the hollow-core optical fiber; absorbing the pump light by the target gas resulting in the periodic modulation of the phase of the probe light; demodulating the phase modulation information of the probe light to obtain the concentration of the target gas, wherein the pump laser is wavelength and/or amplitude modulated. In the present invention, two lasers including a pump laser and a probe laser are used for the measurement, this approach is simple and practical. Also, the use of the hollow-core optical fiber with extremely-small core area greatly increases the optical power density, thus enhances the strength of the detected photothermal signal; this method allows ppb level gas measurement with high selectivity, and is universally suitable for the detection of gases with absorption in near-infrared.

A hybrid Attenuated Total Reflection fiber optic probe device having a radiation source; a detecting system; a core-only solid optical fiber probe tip having an input end and an output end; an input hollow fiber waveguide configured for association with the radiation source at a first end and interconnection with the input end of the core-only solid optical fiber probe tip at a second end; an output hollow fiber waveguide configured for interconnection with the output end of the core-only solid optical fiber probe tip at a first end and association with the detection system at a second end; an inwardly tapered solid fiber input radiation collector element configured at a tapered end for interconnection with the second end of the output hollow fiber waveguide so as to receive radiation from the radiation source; wherein an outside diameter of the core-only solid optical fiber probe tip and an inside diameter of each one of the input hollow fiber waveguide and the output hollow fiber waveguide is such that the interconnection between each one of the input hollow fiber waveguide and the output hollow fiber waveguide and the core-only solid optical fiber probe tip is by means of inserting the input end of the core-only solid optical fiber probe tip into the second end of the input hollow fiber waveguide and inserting the output end of the core-only solid optical fiber probe tip into the first end of the output hollow fiber waveguide, such that the core-only solid optical fiber probe tip is held in the input and output hollow fiber waveguides by means of friction, and wherein an outside diameter of a portion of the inwardly tapered solid fiber input radiation collector element and an inside diameter of the second end of the output hollow fiber waveguide is such that the tapered end of the inwardly tapered solid fiber input radiation collector element is held in the end of the second end of the output hollow fiber waveguide by means of friction.

A hollow-core waveguide structure for guiding an electromagnetic signal, comprising: a core material comprising a predetermined refractive index; and a cladding structure disposed about the core material, wherein the cladding structure has a refractive index that is less than unity; wherein the cladding structure comprises an Epsilon-near-zero (ENZ) metamaterial. The core material comprises air or the like. The cladding structure comprises one of substantially planar sheets disposed about the core material and a substantially tubular structure disposed about the core material. Optionally, the ENZ metamaterial comprises a plurality of nanostructures disposed in a host medium. The plurality of nanostructures comprise a transparent conducting oxide. Alternatively, the cladding structure is manufactured via a self-assembly method.

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).