A multi-core optical fiber includes a plurality of optical waveguides that are at least partially fused to an adjacent optical waveguide. At least some of the optical waveguides are aligned to form a linear array having a major axis generally parallel to the linear array and a minor axis generally perpendicular to the major axis. A linear support structure is fused to the linear array of optical waveguides. A buffer engages and surrounds the outer perimeter defined by the optical waveguides and the linear support structure. The buffer has a buffer modulus of elasticity substantially less than the waveguide modulus of elasticity.

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.

In a multicore optical fiber sensor, an absorptive material integrated into the cladding, or into a waveguide core not used for sensing, may facilitate sensing. The absorptive material is absorptive to light in a wavelength band in which the fiber sensor is configured to operate. Coating such a fiber sensor with a material whose refractive index is smaller than that of the cladding may be done with reduced signal mixing.

The present invention provides a method for manufacturing an optical fiber base material and an optical fiber base material, the method including: arranging a rod containing SiO.sub.2 family glass for core, in a container; pouring a SiO.sub.2 glass raw material solution for cladding layer and a hardener into the container, the glass raw material solution containing a hardening resin; solidifying the glass raw material solution through a self-hardening reaction; and then drying the solidified material and heating the solidified material in chlorine gas, to manufacture an optical fiber base material in which a SiO.sub.2 cladding layer is formed in an outer periphery of the rod containing SiO.sub.2 family glass for core.

There is provided a method for producing a multicore optical fiber while depressurizing holes in a common cladding tube. A production method for a multicore optical fiber includes a preform forming step of forming a common cladding tube having a plurality of holes extending between a first end and a second end, an end-face working step of digging the common cladding tube from the second end to a predetermined depth to forming a third end, a connection step of connecting a glass tube to the second end, an insertion step of inserting core rods into the holes to the third end, a sealing step of sealing the first end, and a drawing step of spinning the multicore optical fiber while depressurizing the holes through the glass tube and combining the common cladding tube and the core rods from the first end.

There is provided a method for producing a multicore optical fiber while reducing the mass of a glass block to be connected to a common cladding tube. A production method for a multicore optical fiber includes in order, a preform forming step of forming a common cladding tube having a plurality of holes extending between a first end and a second end, an insertion step of inserting core rods in the holes in a state in which end portions of the core rods are recessed from the first end, a heat shrinkage step of reducing a diameter of the first end by heating, a sealing step of sealing the holes by connecting a glass block to the first end, and a drawing step of depressurizing insides of the holes from the second end and performing spinning from the first end while combining the common cladding tube and the core rods.

Provided is a method for producing a multicore optical fiber (MCF) in which variations in positions of cores relative to the outer shape of the MCF are small. The method includes: an integrating step of heating a common cladding tube and a core rods, thereby integrating the tube with the core rods to form a core-cladding composite body including a plurality of cores and a common cladding and having a noncircular cross-sectional shape; an outline detecting step of detecting the outline of the composite body; an optical fiber preform forming step of machining the outer circumferential surface of the composite body using results obtained in the outline detecting step to form the preform having a flat surface; and a drawing step of drawing one end of the preform under heating to obtain the MCF. Also provided is a MCF for which a rotation alignment operation is easily performed.

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 preform includes: a cladding glass body that is a cladding of an optical fiber, is cylindrical, and comprises an inner hole along an axial direction; a glass rod accommodated in the inner hole; and a dummy silica rod selected from either one of a first solid dummy silica rod fixed to a first end of the cladding glass body that closes a first end of the inner hole positioned at the first end of the cladding glass body, or a second solid dummy silica rod accommodated and integrated in a connecting glass tube fixed to the first end to close a first tip opening end of the connecting glass tube. A tip seal that closes a second end of the inner hole at a second end of the cladding glass body is provided in the second end of the cladding glass body.

Methods for producing glass components and obtainted glass component, e.g. optical fiber preform. A method includes providing a cladding tube (110) with a longitudinal axis including a first and a second bore separated by a chamfered region (114); inserting a spacer (120) into the first bore; inserting a rod (130) into the first bore (116); moving the spacer (120) into the chamfered section (114), causing the spacer (120) to rotate within the chamfered region (114); and rotating the cladding tube (110) into a vertical orientation, whereby the spacer (120) is prevented from entering the second bore (118) and supports the rod (130). Each portion of the chamfered region has a height perpendicular to the longitudinal axis greater than the height of the second bore. The spacer has a length parallel to the longitudinal axis greater than the height of the second bore but less the distance between the deepest point of the bottom of the chamfered region and an intersection of the top of the chamfered region and the first bore.