Itt Corporation

International Telephone and Telegraph Corporation

Francis I Akers

Mokhtar S Maklad

Kamran Karbassiyoon

Daniel G Fletcher

William L Thomas

A Dahlgren Vaughan

Larry J Raplee

Philip E Foster

John S White

An optical fiber coated with a single ultraviolet cured resin wherein the attenuation losses are less than 0.5 decibels/kilometer. The resin has a tensile modulus of about 7,800 psi. This cable is particularly useful in loosely wrapped cable structures such as open channel or loose tube cables.

Optical fiber with single ultraviolet cured coating

An arrangement for collapsing tubular formations into optical preforms includes a control arrangement which controls the pressure build-up at the downstream end of the tubular formation during all of but the last one of the collapsing increments to control the flow of a gaseous medium through the interior of the tubular formation from an upstream end to and beyond the downstream end of the tubular formation. The magnitude of the back-up pressure is controlled by a set point controller in dependence on the actual value of the back-up pressure, the set point controller being operative for counteracting any deviation from the desired pressure. The set point controller controls the flow-through cross-section of a control valve that admits a pressurized inert gas to a region situated downstream of the downstream end of the tubular formation and also downstream of the point at which the pressure build-up is being measured.

Method of and apparatus for making optical preforms from tubular bodies

An arrangement for collapsing tubular formations into optical preforms includes a control arrangement which controls the ratio of hydrogen to oxygen in an oxyhydrogen burner flame during the collapsing operation toward overabundance of hydrogen when it is desired to increase the degree of evaporation of glass from the outer surface of a tubular proportion being collapsed. This arrangement is used for bringing the ratio of the cross-sectional area of the core region to that of the cladding region in an optical preform resulting from the collapse into or close to a predetermined range, regardless of the initial value of this ratio in the original tubular formation, by evaporating more or less of the glass from the outside of the tubular formation during the collapse.

Method of and apparatus for making optical preforms with a predetermined

The stress-induced birefringent single mode optical fiber includes an optical core having a high refractive index and a high thermal expansion coefficient. An arrangement formed from an optical material having a low refractive index and a low thermal expansion coefficient is disposed to engage the outer surface of the core tangentially at opposite ends of a diameter of the core to establish a stress therein. Air encompasses the remainder of the outer surface of the core to provide a light guiding cladding for the core and, hence, the fiber itself. The arrangement to establish the stress may include a pair of flat plates engaging the outer surface of the core tangentially which are entrapped in a circular tube which is concentric with the core such that air is entrapped between the plates and the circular tube to provide the light guiding cladding. Alternatively, an elliptical tube is provided to engage the outer surface of the core at the minor axis of the elliptical tube to provide the desired stress in the fiber. In this case air is enclosed in the elliptical tube to provide the light guiding cladding.

Stress-induced birefringent single mode optical fiber and a method of

A method for fabricating a fiber with optical cores of diameters between 2 to 20 microns is depicted. A first step includes the fabrication of a step-index preform of predetermined dimensions. The preform is drawn into a conventional fiber by conventional techniques resulting in a fiber having an outer diameter of about 120 microns or larger. The fiber is then emplaced in a glass tube. The tube is collapsed on the fiber by heating the same resulting in a second preform. This preform is again drawn into a fiber by conventional techniques to obtain a final fiber having core dimensions indicative of single mode operation with compatible outer diameters.

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Roanoke, VA, United States of America

Francis I Akers