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.

The vacuum-based methods of forming an optical fiber preform include applying a vacuum to a preform assembly. The preform assembly has at least one glass cladding section with one or more axial through holes, with one or more canes respectively residing in the one or more axial through holes. The opposite ends of the at least one glass cladding section are capped to define a substantially sealed internal chamber. A vacuum is applied to the substantially sealed internal chamber to define a vacuum-held preform assembly. The methods also include heating the vacuum-held preform assembly to just above the glass softening point to consolidate the vacuum-held preform to form the cane-based glass preform. An optical fiber is formed by drawing the cane-based glass preform. The same furnace used to consolidate the vacuum-held preform can be used to draw the optical fiber.

This invention provides a manufacturing method for an optical fiber. In this invention, when the core layer loose body and the cladding layer loose body are deposited, the oxyhydrogen flame is used make a temperature of an interface between the core layer and the cladding layer rise, such that silicon dioxide at the interface appropriately contracts to form an isolation layer with a relatively high density. In addition, in this invention, a hollow glass tube is used as a target rod, and the hollow glass tube which is the target rod is directly connected with the core layer loose body. During the subsequent dehydration, not only a dehydration atmosphere penetrates from the outside to the inside of the cladding layer loose body, but also the dehydration atmosphere directly enters the core layer through the hollow glass tube.

A method for manufacturing an optical fiber preform including a core part and a cladding part is disclosed. The method includes: adding an alkali metal to an inner surface of a silica-based glass pipe; etching the inner surface of the silica-based glass pipe to which the alkali metal is added; making a glass rod by collapsing the silica-based glass pipe after the etching; and making an optical fiber preform using the glass rod. The silica-based glass pipe is heated in the adding such that a surface temperature of the silica-based glass pipe falls within a temperature range of 1500 C. or higher to lower than 2000 C.

The embodiment relates to an optical connection component including a bent optical fiber having a bent portion including a region where a curvature of the bent portion is maintained at 0.4 [l/mm] or more while substantially no bending stress remains. The bent optical fiber comprises a core, a first cladding, a second cladding, and a third cladding. Based on the third cladding, a relative refractive index difference 1 of the core, a relative refractive index difference 2 of the first cladding, and a relative refractive index difference 3 of the second cladding satisfy relationships of 1>2>3 and 3<0.5 [%]. The product V3 of the 3 and a cross-sectional area S of the second cladding is less than 200 [%.Math.m.sup.2]. The curvature in the bent portion is 0.6 [l/mm] or less over an entire length of the bent portion.

According to embodiments of the present invention, a fiber preform or an optical fiber is provided. The fiber preform or the optical fiber includes a core region, and a cladding arrangement comprising a first cladding region comprising a plurality of rods entirely surrounding the core region, and a second cladding region in between the core region and the first cladding region, the second cladding region comprising a plurality of tubes, wherein a plurality of splits are defined in the second cladding region. According to further embodiments of the present invention, a method for forming a fiber preform and a method for forming an optical fiber are also provided.

An optical fiber comprises, from a center to a periphery, a fiber core of undoped silica; a cladding layer; and a coating of polyacrylate, wherein the fiber core has a radius of 5 to 7 m and an ellipticity of less than 1.5%, the cladding layer with an ellipticity of less than 0.4% comprises inner, intermediate, and outer cladding layers, the inner cladding layer being doped with fluorine of 5 to 12 m thickness, and refractive index difference to fiber core of 0.4 to 0.2%, the outer cladding layer being undoped quartz of 25 to 45 m thickness, and the coating comprises an inner coating of 25 to 40 m thickness, and an outer coating of 25 to 35 m thickness and an ellipticity of less than 2%. The optical fiber has high durability and large effective transmission area, a method and system for preparing such optical fiber are also disclosed.

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.

The embodiment relates to an optical connection component including a bent optical fiber having a bent portion including a region where a curvature of the bent portion is maintained at 0.4 [1/mm] or more while substantially no bending stress remains. The bent optical fiber comprises a core, a first cladding, a second cladding, and a third cladding. Based on the third cladding, a relative refractive index difference 1 of the core, a relative refractive index difference 2 of the first cladding, and a relative refractive index difference 3 of the second cladding satisfy relationships of 1>2>3 and 3 <0.5[%]. The product V3 of the 3 and a cross-sectional area S of the second cladding is less than 200 [%.Math.m.sup.2]. The curvature in the bent portion is 0.6 [1/mm] or less over an entire length of the bent portion.

A rare earth-doped double-clad optical fiber includes a rare earth ion-doped fiber core, an inner cladding layer, and an outer cladding layer. A cross section of the inner cladding layer is a non-circular plane including at least two arcuate notches. According to the provided optical fiber, optical processing can be performed on a preform without changing a preform preparation process and a drawing process. The inner cladding is designed to have a non-circular planar structure having a cross section with at least two arcuate notches. While maintaining the same light absorption efficiency of pump light within the cladding layer, a preform polishing process is simplified, a risk of cracking the preform during polishing of multiple surfaces and a risk of contamination of the preform caused by impurities are reduced, wire drawing control precision is better, and comprehensive performance of the optical fiber is improved.