Bend resistant multimode optical fibers are disclosed herein. Multimode optical fibers disclosed herein comprise a core region and a cladding region surrounding and directly adjacent to the core region, the cladding region comprising a depressed-index annular portion comprising a depressed relative refractive index.

Bend resistant multimode optical fiber

A rod-in-tube method for producing a glass preform for use in the fabrication of an optical fiber, which comprises steps of inserting a glass rod (13) as a core material in a glass tube (12) as a cladding material, fusing and closing one end of the cladding material, filling a gap between the core and cladding materials with an atmosphere containing at least one gaseous halogen-containing compound and then heating the core and cladding materials at a temperature not lower than 1,900°C to collapse the gap between them and to fuse them together, from which glass preform, an optical fiber with low attenuation of light transmission is fabricated.

Method for producing glass preform for optical fiber

A fiber for optical transmission composed of a core having a substantially parabolic distribution of refractive index, a first cladding layer formed around the core having a refractive index equal to that of the periphery of the core and a thickness of 1/100 to 1/20 the diameter of the core, a second cladding layer formed around the first cladding layer having a refractive index smaller than that of the first cladding layer, and a third cladding layer formed around the second cladding layer having a refractive index greater than that of the second cladding layer. The fiber for optical transmission having such a structure has a broad bandwidth of transmitted light.

Fiber for optical transmission

The present invention embraces a multimode optical fiber that includes a central core having an alpha-index profile, an inner cladding, a depressed trench, and an outer cladding (e.g., an outer optical cladding). Typically, the central core's alpha-index profile has a minimum refractive index at the central core's radius that corresponds to a refractive index difference with respect to the outer cladding. The optical fiber achieves reduced bending losses and a high bandwidth with a reduced cladding effect for high-data-rate applications.

High-Bandwidth Multimode Optical Fiber Having Reduced Bending Losses

Receiver design for high-speed ptical-fiber systems

The application of low loss optical fibers in optical communication systems requires that the glass fibers are suitably packaged into a cable. This invention provides a system of multiple optical fibers between two tapes or films, one of which holds the fibers on the film by pressure-sensitive adhesive and in spaced relation to one another. The fibers are covered by a second film, preferably thinner than the first film, and secured to the first film along the edges of the films to provide a laminated structure suitable for cabling. Spacers between the films eliminate asymmetric pressure of the covering film against the optical fibers which are nearest to the edges of the films; and the spacers are preferably strength members for stiffening the laminate.

Multiple fiber laminate for optical waveguides

A method of forming a preform or blank for a high bandwidth gradient index optical filament, the preform itself and the resulting optical filament is disclosed. The preform which ultimately forms the optical filament includes a barrier layer between a tubular starting member which comprises the cladding and the core, the index of refraction of the barrier layer being equal to or less than the index of refraction of the tubular starting member; there being no step increase in the index of refraction of the barrier layer at the barrier layer-cladding interface nor of the core at the core-barrier layer interface of the optical filament. The barrier layer is formed from a base glass, a first dopant B2 O3, and at least one other dopant which is maintained substantially constant in the barrier layer and then gradually varied during the formation of the core. The quantity of B2 O3 is also maintained substantially constant in the barrier layer but then gradually decreased during the formation of the core.

High bandwidth optical waveguides and method of fabrication

A method of forming a preform or blank for a high bandwidth gradient index optical filament, the preform itself and the resulting optical filament is disclosed. The preform which ultimately forms the optical filament includes a barrier layer between a tubular starting member which comprises the cladding and the core, the index of refraction of the barrier layer being equal to or less than the index of refraction of the tubular starting member; there being no step increase in the index of refraction of the barrier layer at the barrier layer-cladding interface nor of the core at the core-barrier layer interface of the optical filament. The tubular starting member is formed of a base glass and at least one dopant, the index of refraction of the tubular starting member being in excess of said base glass. The barrier layer is formed from a base glass and at least one dopant which is maintained substantially constant in the barrier layer. The core is formed of a base glass and at least one dopant which is gradually varied during the formation of the core, the core being free of B2 O3.

High bandwidth optical waveguide having B2 O3 free core and method of fabrication

This optical fiber cable has the optical fibers adhered to a support. An assembly including the fibers and the support is carried by a core element having a helical channel in which the fiber assembly is located and free to adjust itself to accommodate bending of the cable without subjecting the optical fibers to pressure or to bends that are excessively sharp. The construction also avoids pressure on the optical fibers from binders, core tapes, or the cable sheath when the cable is bent. It also avoids micro-bending losses. Locating of the optical fibers closer to the cable axis further decreases bending losses.

Optical fiber cable construction

An improved sol-gel process for fabricating large, crack-free gel monoliths (e.g., of silica) is described in which a specially-tailored gel microstructure is provided by adjusting the relative concentrations of an alcohol diluent (e.g., ethanol) and/or one or more catalysts (e.g., HC1 and HF). Controlled variations in the gel's average pore radius, bulk density, rupture modulus, and elastic modulus over a wide range can be tailored in this fashion. This enables the process to be optimized for the particular application involved.

Arnab Sarkar

Papers

Multiple fiber laminate for optical waveguides

High bandwidth optical waveguides and method of fabrication

High bandwidth optical waveguide having B2 O3 free core and method of fabrication

Optical fiber cable construction

Sol-gel process for providing a tailored gel microstructure