Stacks of optical fiber ribbons closely bound by respective buffer encasements, associated methods, and associated fiber optic cables

A fiber optic cable, comprising:

• a stack of optical fiber ribbons extending in a longitudinal direction, wherein each optical fiber ribbon comprises a laterally extending array of longitudinally extending optical fibers bonded together as a unit, each optical fiber ribbon comprises a pair of longitudinally extending opposite edges and a pair of longitudinally extending opposite surfaces that extend laterally between the edges, and each optical fiber ribbon has a thickness defined between its opposite surfaces;
• and
• a relatively thin sheath comprising longitudinally extending interior and exterior surfaces, wherein the interior surface extends around and defines a longitudinally extending passage that contains the stack so that for each optical fiber ribbon the interior surface of the sheath engages each of the edges of the optical fiber ribbon, with the interior surface closely bounding and engaging the periphery of the stack, and in an end elevation view of the sheath at least a majority of the sheath has a thickness defined between the interior and exterior surfaces that is not substantially greater than the thickness of each of the optical fiber ribbons, and wherein the interior surface of the sheath is adhered to the stack.

A twisted fiber optic cable, comprising:

• a stack of optical fiber ribbons extending in a longitudinal direction, wherein each optical fiber ribbon comprises a laterally extending array of longitudinally extending optical fibers bonded together as a unit, and the stack is in a longitudinally twisted configuration;
• and
• a thin sheath comprising longitudinally extending interior and exterior surfaces, wherein the interior surface extends around and defines a longitudinally extending passage containing the stack, the interior surface closely bounds and engages the periphery of the stack, the sheath alone is sufficiently rigid to hold the stack in the longitudinally twisted configuration, and the sheath is thin such that the exterior surface of the sheath defines ridges that correspond to the twist of the stack, wherein the ridges are at corners of the sheath that are respectively positioned at corners of the stack.

A method of manufacturing a fiber optic cable, comprising the steps of:

• advancing in a longitudinal direction a longitudinally extending stack of optical fiber ribbons;
• longitudinally twisting the stack;
• retaining the twist by encasing the twisted stack solely in a one-piece buffer encasement, wherein the buffer encasement has an interior surface that closely bounds and engages the periphery of the stack, the buffer encasement alone is sufficiently rigid to retain the twist, each optical fiber ribbon has a pair of opposite edges that extend in the longitudinal direction, and for each optical fiber ribbon the interior surface of the buffer encasement engages each of the edges of the optical fiber ribbon.

A method of manufacturing a fiber optic cable, comprising the steps of:

• advancing in a longitudinal direction a longitudinally extending stack of optical fiber ribbons;
• longitudinally twisting the stack;
• retaining the twist, comprising the step of encasing the twisted stack in a buffer encasement, wherein the buffer encasement has an interior surface that closely bounds and engages the periphery of the stack and is sufficiently rigid to retain the twist, and the step of encasing the twisted stack in an buffer encasement comprises the step of wrapping material helically around the twisted stack.