A hollow-core antiresonant fiber (HC-ARF) with nested supporting rings (NSRs) has a fiber structure that includes from the inside out a fiber core, a first silica antiresonant ring (SARR), a first air antiresonant ring (AARR), a second SARR, a second AARR and an external silica wall. The fiber structure further includes a first NSR within the first AARR and a second NSR within the second AARR. The HC-ARF with NSRs has advantages and benefits of low confined loss (CL), large bandwidth, simple structure and very good bending characteristics. Therefore, the application fields of HC-ARF are greatly expanded.

A multi-core fiber includes: a plurality of cores; and a cladding portion formed around outer peripheries of the cores. Further, the cores each have a propagation characteristic conforming to any one of a plurality of standards for optical propagation characteristics, and of the cores, cores that are closest to each other conform to standards different from each other.

A method for manufacturing an optical fiber preform includes: producing a core preform including a core portion made of transparent glass and a first cladding layer obtained by adding fluorine to the core portion; and forming, on an outer periphery of the first cladding layer, a second cladding layer made of glass having a refractive index higher than that of the first cladding layer. Further, a refractive index profile is formed in the first cladding layer due to a fluorine concentration profile, the refractive index profile being provided at least near a boundary surface with the second cladding layer and having a profile such that a refractive index difference between a refractive index of the first cladding layer and a refractive index of the second cladding layer decreases in accordance with a reduction in a distance from the boundary surface with the second cladding layer.

A hollow-core fiber with a single layer of robust anti-resonant optical arches is disclosed, which is designed and made of infrared soft glass and allows the transmission of mid- to long-infrared wavelengths (1-15 microns). Each curved arch is solidly attached at two locations on the outer solid region surface and together the arches define the core diameter. The thickness and spacing between the arches are selected to minimize the fiber transmission loss <1 dB/m at wavelengths in the mid- to long-infrared where the infrared soft glass has high absorption >30 dB/m. A hollow-core preform with anti-resonant arches is made by extrusion of infrared soft glasses through a die specifically designed to produce the hollow-core fiber with anti-resonant arches.

A hollow-core fiber with a single layer of robust anti-resonant optical arches is disclosed, which is designed and made of infrared soft glass and allows the transmission of mid- to long-infrared wavelengths (1-15 microns). Each curved arch is solidly attached at two locations on the outer solid region surface and together the arches define the core diameter. The thickness and spacing between the arches are selected to minimize the fiber transmission loss <1 dB/m at wavelengths in the mid- to long-infrared where the infrared soft glass has high absorption >30 dB/m. A hollow-core preform with anti-resonant arches is made by extrusion of infrared soft glasses through a die specifically designed to produce the hollow-core fiber with anti-resonant arches.

This application relates generally to an optical fiber for the delivery of infrared light where the polarization state of the light entering the fiber is preserved upon exiting the fiber and the related methods for making thereof. The optical fiber has a wavelength between about 0.9 m and 15 m, comprises at least one infrared-transmitting glass, and has a polarization-maintaining (PM) transverse cross-sectional structure. The infrared-transmitting, polarization-maintaining (IR-PM) optical fiber has a birefringence greater than 10.sup.5 and has applications in dual-use technologies including laser power delivery, sensing and imaging.

An optical fiber includes an outer diameter less than 220 m, a glass fiber that includes a glass core and a glass cladding, a primary coating, and a secondary coating. The glass cladding surrounds and is in direct contact with the glass core. The primary coating surrounds and is in direct contact with the glass fiber. The primary coating can have a Young's modulus less than 0.5 MPa and a thickness less than 30.0 m. The secondary coating surrounds and is in direct contact with the primary coating. The secondary coating can have a thickness less than 27.5 m. A pullout force of the optical fiber can be less than a predetermined threshold when in an as-drawn state. The pullout force may increase by less than a factor of 2.0 upon aging the primary and secondary coatings on the glass fiber for at least 60 days.

A hollow-core antiresonant fiber (HC-ARF) with nested supporting rings (NSRs) has a fiber structure that includes from the inside out a fiber core, a first silica antiresonant ring (SARR), a first air antiresonant ring (AARR), a second SARR, a second AARR and an external silica wall. The fiber structure further includes a first NSR within the first AARR and a second NSR within the second AARR. The HC-ARF with NSRs has advantages and benefits of low confined loss (CL), large bandwidth, simple structure and very good bending characteristics. Therefore, the application fields of HC-ARF are greatly expanded.

A method of forming an optical fiber preform includes: flowing a silicon halide and an oxidizer inside of a substrate tube, wherein a molar ratio of the silicon halide to the oxidizer is from about 1.5 to about 5.0; applying a plasma to the substrate tube to heat the substrate tube to a temperature of from about 1000 C. to about 1700 C.; and depositing silica glass comprising a halogen inside the substrate tube.

An optical fiber includes an outer diameter less than 220 m, a glass fiber that includes a glass core and a glass cladding, a primary coating, and a secondary coating. The glass cladding surrounds and is in direct contact with the glass core. The primary coating surrounds and is in direct contact with the glass fiber. The primary coating can have a Young's modulus less than 0.5 MPa and a thickness less than 30.0 m. The secondary coating surrounds and is in direct contact with the primary coating. The secondary coating can have a thickness less than 27.5 m. A pullout force of the optical fiber can be less than a predetermined threshold when in an as-drawn state. The pullout force may increase by less than a factor of 2.0 upon aging the primary and secondary coatings on the glass fiber for at least 60 days.