Tapered core fibers are produced using tapered core rods that can be etched or ground so that a fiber cladding has a constant diameter. The tapered core can be an actively doped core, or a passive core. One or more sleeving tubes can be collapsed onto a tapered core rod and exterior portions of the collapsed sleeving tubes can be ground to provide a constant cladding diameter in a fiber drawn from the preform.

An optical fiber bundle manufacturing apparatus includes: a winding member; a guide member movable in a direction parallel to a rotary axis, the guide member being configured to guide an optical fiber wire to any one of first winding positions, a converging winding position and second winding positions; and a processor configured to perform processing to move the guide member such that a first branching portion branching into p branches, a converging portion converging the first branching portion branching into p branches into one, a second branching portion branching into q branches, and a connecting portion connecting the first branching portion and the second branching portion are formed in this order by the optical fiber wire.

An optical fiber bundle manufacturing apparatus includes: a winding member; a guide member movable in a direction parallel to a rotary axis, the guide member being configured to guide an optical fiber wire to any one of first winding positions, a converging winding position and second winding positions; and a processor configured to perform processing to move the guide member such that a first branching portion branching into p branches, a converging portion converging the first branching portion branching into p branches into one, a second branching portion branching into q branches, and a connecting portion connecting the first branching portion and the second branching portion are formed in this order by the optical fiber wire.

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.

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 drawing furnace heating element includes a heat generator including: a tubular resistance heating element in which at least a part of an optical fiber preform is disposed in a through-hole; a first portion extending, from a first end portion, over a predetermined section along a longitudinal direction; and a second portion disposed closer to a second end portion than the first portion. The second portion has a wall thickness on a side of the first end portion being equal to or larger than a wall thickness of the first portion. The wall thickness of the second portion increases toward a side of the second end portion from the side of the first end portion.

An optical fiber manufacturing apparatus includes a heating furnace configured to heat and melt an optical fiber preform; a pulling mechanism configured to adjust an outer diameter of a glass optical fiber by drawing out the glass optical fiber from the optical fiber preform melted through the heating by the heating furnace, and to draw the glass optical fiber that has been adjusted in outer diameter; a coating mechanism configured to apply a predetermined resin on an outer circumference of the glass optical fiber that has been adjusted in outer diameter; and a transport mechanism configured to returnably retract the coating mechanism from a passage route of the glass optical fiber.

An optical fiber manufacturing apparatus includes a heating furnace configured to heat and melt an optical fiber preform; a pulling mechanism configured to adjust an outer diameter of a glass optical fiber by drawing out the glass optical fiber from the optical fiber preform melted through the heating by the heating furnace, and to draw the glass optical fiber that has been adjusted in outer diameter; a coating mechanism configured to apply a predetermined resin on an outer circumference of the glass optical fiber that has been adjusted in outer diameter; and a transport mechanism configured to returnably retract the coating mechanism from a passage route of the glass optical fiber.

Provided is an image guide fiber that improves image quality while preventing a manufacturing problem. The image guide fiber according to the present disclosure has a numerical aperture NA in the range of 0.70 to 0.90. A linear thermal expansion coefficient difference , which is a value obtained by subtracting a linear thermal expansion coefficient .sub.2 at from 100 to 300 C. of clad glass, from a linear thermal expansion coefficient .sub.1 at from 100 to 300 C. of core glass, is in the range of 310.sup.7 C. to 1510.sup.7/ C. A glass-transition temperature Tg.sub.1 of the core glass is higher than a glass-transition temperature Tg.sub.2 of the clad glass. A core occupancy area ratio is 25% or more. A pixel density is 0.1 pixel/m.sup.2 or more.

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.