An optical fiber manufacturing method includes setting a first holding member and a rod inside a glass pipe, the first holding member made of glass and having plural holes formed, so that the rod is supported by the first holding member; filling glass particles between the rod and a glass pipe inner wall; holding the rod such that the rod and the filled glass particles are enclosed by the glass pipe inner wall and the first and second holding members, and sealing one end of the glass pipe and manufacturing an intermediate; and manufacturing an optical fiber from the intermediate, wherein a bulk density of the first and second holding members is set with reference to a bulk density of a filling portion made from the glass particles, and the predetermined range is determined according to a core diameter permissible variation range in its longitudinal direction.

A polarization-maintaining optical fiber includes at least one polarization maintaining core, a first cladding surrounding the at least one polarization maintaining core, and a second cladding surrounding the first cladding. The at least one polarization maintaining core includes a core and a pair of low-refractive-index portions each having a refractive index lower than a refractive index of the core. In a cross section, at least a portion of an outer periphery of each of the pair of low-refractive-index portions is in contact with the core, and an outer periphery of the core, excluding portions each being in contact with the low-refractive-index portions, has a circular shape. A maximum value of an absolute value of a residual stress in the cross section is 100 MPa or less. A mode-field flattening f is 0.05 to 0.40 at any wavelength within a range of 850 nm to 1625 nm.

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 having a core comprising silica and greater than 1.5 wt % chlorine and less than 0.5 wt % F, said core having a refractive index .sub.1MAX, and an inner cladding region having refractive index .sub.2MIN surrounding the core, where .sub.1MAX>.sub.2MIN.

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.

Provided is an optical fiber in which a primary coating layer and a secondary coating layer are formed on an outer circumference of a bare optical fiber including a core and a cladding. A Young's modulus of the primary coating layer is 0.1 to 1.0 MPa, a relationship between lateral rigidity D and flexural rigidity H of the optical fiber as expressed by formulas below satisfies D/H.sup.2310.sup.17 N.sup.1 m.sup.6, the primary coating layer contains 0.3 to 2.0 wt % of a photoinitiator including phosphorus, and the primary coating layer contains polypropylene glycol having a weight-average molecular weight of 1000 to 5000. The formulas include $H=H_g+H_s=r_g^4{E}_g+\left(r_{s_{\mathrm{.Math.}}}^4-r_p^4\right)E_s\mathrm{and}$$D=0.897E_p+2.873(E_{}$

An optical fiber having a core comprising silica and greater than 1.5 wt % chlorine and less than 0.5 wt % F, said core having a refractive index .sub.1MAX, and a inner cladding region having refractive index .sub.2MIN surrounding the core, where .sub.1MAX>.sub.2MIN.

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 manufacturing method of an optical fiber preform used to produce an optical fiber includes: etching a surface of a core preform that forms a core of the optical fiber with a plasma flame in a chamber; obtaining a porous preform by depositing glass particles on an etched surface of the core preform to form an outside vapor-deposited layer that forms a cladding of the optical fiber in a state where the core preform is put into the chamber; and heating and sintering the porous preform. When obtaining the porous preform, the outside vapor-deposited layer is formed by repeatedly performing the deposition of the glass particles multiple times through supply of source material gas. In a first deposition among the multiple times of deposition of the glass particles, a flow rate of the source material gas is less than or equal to 50% of a stable value.

Provided is an optical fiber in which a primary coating layer and a secondary coating layer are formed on an outer circumference of a bare optical fiber including a core and a cladding. A Young's modulus of the primary coating layer is 0.1 to 1.0 MPa, a relationship between lateral rigidity D and flexural rigidity H of the optical fiber as expressed by formulas below satisfies D/H.sup.2310.sup.17 N.sup.1m.sup.6, the primary coating layer contains 0.3 to 2.0 wt % of a photoinitiator including phosphorus, and the primary coating layer contains polypropylene glycol having a weight-average molecular weight of 1000 to 5000. The formulas include

[00001]$H=H_g+H_s=.Math..Math.r_g^4.Math.E_g+\left(r_{s_{\mathrm{.Math.}}}^4-r_p^4\right).Math.E_s.Math..Math.\mathrm{and}$$D=0.897.Math.E_p+2.873.Math.\left(E_s-E_p\right).Math.{\left(\frac{E_p}{E_s}\right)}^{0.8311}.Math.{\left(2.Math.\frac{r_s-r_p}{r_s-r_g}\right)}^{1.189},$ where r represents a radius (m), E represents a Young's modulus (Pa), a subscript g represents glass (the bare optical fiber), a subscript p represents the primary coating layer, and a subscript s represen