Abstract: An optical fiber (21) which has been drawn from a preform (22) is moved into and through a chamber (38) of a housing. A source of vacuum is connected to the chamber to prevent the attachment of air pockets to the optical fiber as it is being moved through the chamber and through an opening of a die. The die includes a flow path (55) which is substantially normal to the path of travel of the optical fiber and the die opening is substantially larger than the diameter of the optical fiber. The thickness of the flow path in a direction along the path of travel is sufficiently small so as to prevent the recirculation of the coating material in the vicinity of the point of application to the optical fiber. Also, the fiber draw rate, the pressure of the coating material the direction of the flow path relative to the longitudinal axis of the optical fiber and the diameter of the die opening are such that a gap forms between the coating material and the die.

Abstract: Methods of and apparatus for winding strand such as optical fibers on altate spools and for storing and protecting from damage coiled end portions of the strand to be wound on the spools in which the coils are clamped laterally of the coils with forces applied parallel to the axis of the coils. The methods and apparatus of the invention may be used for urging portions of the strand being fed to the spools and associated strand storage and clamping devices against the peripheral surfaces thereof to aid in the transfer of the distribution of the strand from one spool to the other spool.

Abstract: An optical fiber cable (20) includes a core (21) comprising at least one optical fiber (24) which is enclosed in a tubular member (34) and which includes a sheath system (40). The sheath system includes two strength members 42--42 which extend linearly longitudinally along the cable parallel to a longitudinal axis (29) of the cable. The strength members are enclosed in a plastic jacket (46). The strength members have predetermined relative tensile and compressive stiffnesses. The stiffnesses are such that the strength members are capable of withstanding expected compressive as well as tensile loading and are coupled sufficiently to the jacket to provide a composite arrangement which is effective to inhibit contraction and which controls the position of the neutral axis during bending while providing suitable flexibility.

Abstract: An optical fiber cable (20) includes a core (21) comprising plurality of units (22--22). Each unit is formed by a plurality of optical fibers (24--24) which are assembled together without intended stranding. Each of the optical fibers includes a core, and inner and outer claddings with the inner cladding characterized by an index of refraction depressed from that of the outer cladding. The ratio of the inner cladding diameter to the core diameter and the ratio of the difference in the indices of refraction of the inner and outer claddings to the difference in indices of refraction between the core and the inner cladding are such that each optical fiber is capable of operation in a single mode fashion at a predetermined wavelength. Also, the difference between the indices of refraction of the core and the inner cladding is sufficiently high to cause each fiber to be substantially insensitive to microbending.

Abstract: An optical fiber cable (20) includes a core (21) comprising a plurality of units (22--22). Each unit is formed by a plurality of optical fibers (24--24) which are assembled together without intended stranding. The plurality of units are enclosed in a common tube (34) which provides a predetermined packing density and which is substantially parallel to the longitudinal axis of the cable. In one embodiment, a waterblocking material (36) is disposed within the tube to fill the interstices between the optical fibers and between the units. The waterblocking material is such that its critical yield stress does not exceed about 70 Pa at 20.degree. C. and such that it has a shear modulus of less than about 13 KPa at 20.degree. C. The common tube is enclosed with non-metallic or metallic strength members and a plastic inner jacket and by another layer of strength members and by a plastic outer jacket.

Abstract: A closure (20) for optical fiber cables each including at least one optical fiber (38) and a metallic shield (47) enclosed in a jacket (48) includes a splice tray (22), a bonding and gripping assembly (26) and mating cover portions (27, 29). The splice tray includes provisions (24) on one side thereof for holding an optical fiber splice such as one which may be made by a rotary splice and a raceway (51) for routing the optical fiber to the splice. Metallic conductors (45--45), if included in the cables, may be spliced on an opposite side of the splice tray. The bonding and gripping assembly is attached to the splice tray and includes opposed projecting portions (78--78) and ferrules (71--71). Each cable to be spliced is routed to the bonding and gripping assembly to cause each projecting portion to be inserted into a cable end between the shield and core thereof to establish an electrical connection with the shield and to cooperate with the associated ferrule to grip the cable end portion.

Abstract: Method and apparatus are provided for overcladding a preform rod (22). The preform rod is aligned with and inserted into an overcladding tube (30). The outer diameter of the preform rod and the inner diameter of the tube are such that the clearance between the tube and the rod does not exceed a predetermined value. Successive increments of length of the tube and rod therein are subjected to a controlled zone of heat while the pressure inside the tube is maintained at a value which is substantially less than that outside the tube. This causes the tube to be collapsed onto the preform rod to provide an overclad preform and subsequently a drawn optical fiber in which the overcladding is substantially concentric with respect to the optical fiber core.

Abstract: A flame and smoke resistant optical fiber cable (20) having a relatively small diameter includes a core comprising a ribbon array or a plurality of individual fibers and a sheath system. The sheath system includes an impregnated fiber glass tape (35) which has been wrapped about the core. The tape is impregnated with a solution system which comprises a micaceous constituent, a fluoropolymer constituent and a lubricant such as silicone. The impregnated system provides the tape and hence the cable with unexpectedly superior fire retardant and smoke resistance properties so that the cable is suitable for plenum and riser use. Advantageously, the thickness of the tape impregnated with such a system is relatively thin which is helpful in maintaining a relatively small diameter for the cable. An all dielectric strength member system is disposed between the tape and a plastic jacket (37).

Abstract: During the heating of a moving wire (21) such as when the wire is being aaled, the wire is heated in such a manner that the energy applied to each successive increment of length of the wire is substantially constant. This is accomplished by causing an integral number of half cycles of alternating curent to be applied to each successive increment of length of the wire as the increments are moved from one sheave to another in an annealer (20). In one embodiment, the integral number of half cycles is achieved by adjusting the speed at which the wire is being advanced between two sheaves of the annealer in a manufacturing line. This also may be accomlished by adjusting the distance between the sheaves in an annealing leg of the annealer, or by adjusting the frequency of the applied power source.

Abstract: A communications cable comprising a core of at least one transmission media and a plastic jacket includes provisions for preventing the movement of water within the cable. A water blockable yarn (33) or strip (35) is interposed between the core and the jacket (32) and extends either linearly along the cable or is wrapped helically about a portion of the sheath system. In any plane along the cable which is transverse to the longitudinal axis of the cable, the yarn or the strip extends about an insubstantial portion of an inner periphery of the cable. As a result, any desired bond between the jacket and an underlying element of the cable sheath system is discontinuous for only an insignificant portion of the peripheral surface of contact. The yarn may be one which has been treated with a superabsorbent material whereas the strip may comprise a substrate strip which has been impregnated with a superabsorbent material which upon contact with water swells and inhibits the movement of water within the cable.

Abstract: An optical fiber connector (20) includes two plug assemblies (37--37) each including a cylindrically shaped plug (40) extending from within a cap (70). An end of each cap is adapted to be secured to a coupling housing (92) to cause the plug which extends from the cap to be received in a sleeve (105) disposed in the housing. An optical fiber cable (22) extends through a cable entrance end of the cap and has an end portion of its optical fiber terminated by theplug. An extender(85) of the cap is secured thereto and extends along the cable a distance to a location where portions (91--91) thereof are closely adjacent to the cable. Bending forces applied to the cable are transferred at the location to the extender and then to the cap. This avoids the transfer of those forces to the plug which otherwise could cause the plug to turn pivotally about an interior lip of the cap and result in an optical disconnection of the plug from the other plug in the sleeve.

Abstract: An optical fiber cable includes a fluted strength member core (22) which comprises a plurality of ribs (26--26) extending radially from a center portion and a plurality of grooves (28--28), each groove being disposed between two adjacent ribs. The fluted core is such that the ratio of the diameter of a circle (41) which passes through an outermost surface of each rib to the diameter of a circle (44) through the inverts of the grooves does not exceed a predetermined value and cooperates with a reference width of each rib to allow a plurality of optical fibers to be disposed in each groove. Further, the geometry of the fluted core is such that the optical fibers are capable of longitudinal and lateral movement in the grooves. A core wrap (50) which may be made of a flame retardant material encloses the fluted core and a jacket (60) which is made of a plastic material encloses the core wrap.

Abstract: A communications distribution system (20) provides service for local business and residential premises with fewer splice points required and less waste than encountered in prior art systems. The system includes a feeder distribution interface (60) which is served by a feeder cable or by a carrier system and at least one group interface (61) which is disposed to serve customers' premises. A backbone cable segment (62) extends from the feeder distribution interface to a single group interface and is capable of providing service to a plurality of customer premises. Each customer's premises is served by a single distribution service cable (66) which is connected to a backbone cable segment at a group interface. The single distribution service cables for an area may extend radially or laterally from a group interface.

Abstract: A biconic connector includes two plugs (44--44) each terminating a single fiber optical cable (55) and each including a conically shaped end portion (50). In order to minimize loss through a connection, the axis of an end portion of the optical fiber in the conically shaped end portion of the plug should be substantially coincident with the axis of revolution of the conically shaped end portion. This is accomplished by holding the plug in a fixture such that its conically shaped end portion is exposed and the fixture adapted to be turned about an axis of rotation (105). Scattered light from a laser (166) directed toward a gauging length (100) of optical fiber in a passageway of the plug and extending beyond an end face thereof as the plug is turned rotatably is received on a target area. The fixture is turned pivotally to cause the axis of the gauging fiber to parallel the axis of rotation.

Abstract: In an optical fiber connector (20), an alignment sleeve (66) for holding two conically shaped portions (30-30) of plugs (24-24) each of which terminates an optical fiber (25) includes two conically shaped cavities (68,70) communicating through a common plane (72). A peripheral end portion of at least one end of the sleeve is provided with a notch (86). The notch is adapted to receive a key (43) which projects from a plug as the plug is inserted into the sleeve cavity. This locks the plug in the sleeve and prevents unintended rotation of the plug relative to the sleeve which could abrade opposing end faces of the fibers when a threaded cap in which the plug is mounted is turned into a coupling housing (57) which supports the sleeve and which already has another plug mounted therein.

Abstract: A duplex optical fiber connector (20) includes a housing (21) having a cable entrance end and a plug end. At the cable entrance end, an optical fiber cable (23) which includes two individually buffered optical fibers (25--25), strength member yarn (29) and a plastic jacket is routed into a flanged end of a bushing (45) having a tapered passageway therethrough. The bushing is supported in a base (22) of the housing. The jacket is removed from the portion of the cable which extends from the cable entrance end to the plug end and the yarn is positioned between two conformable, truncated conically shaped, substantially smooth surfaces which define the passageway of the bushing and a truncated conically shaped wedge (50) which is received in the passageway. The wedge includes a bore through which the optical fibers extend. This locking arrangement in which the yarn makes no retroflexed turns is self-enhancing when tensile forces are applied to the cable.

Abstract: An optical fiber cable particularly suited for use in building distribution systems includes a core which comprises a plurality of coated optical fibers (22--22) with each being enclosed in a plastic buffer (26). The optical fibers are individually or collectively enclosed in a fibrous strength member. Over the strength member in each of several embodiments is provided an outer jacket comprising a plastic material having excellent resistance to flame spread and smoke evolution. The plastic material comprising the jacket is disposed about the strength member and decoupled sufficiently therefrom to avoid the introduction of microbending stresses in the optical fiber. This may be accomplished by vacuum sizing the plastic material which has been tubed over an advancing optical fiber core as the plastic material is being drawn down onto the strength member.

Abstract: An optical fiber cable includes a core (22) comprising optical fibers (24-24) in ribbon or single fiber form and a sheath system (50) which provides flexibility for ease of handling and installation, strength to resist tensile and torsional stresses and rodent and/or lightning protection. The core is enclosed by a tube (28) which is made of a plastic material, a shield system (52) and outer plastic jacket (54). The shield system provides rodent and/or lightning protection. Strength is provided by a plurality of longitudinally extending strength members (58-58) which are disposed in a single layer concentric with the core and which in a preferred embodiment are disposed adjacent to an outer surface of the shield and with substantial portions of their perpheries embedded in the plastic of the outer jacket.

Abstract: An aerial service wire (20) includes a jacket (40) having a generally rectangularly shaped cross section and comprising a polyvinyl chloride plastic material. Enclosed by the jacket are two strength members (36--36) each of which includes a plurality of filaments and each of which is impregnated with a material which is compatable with that of the jacket. The strength members are disposed along an axis (42) of the cross section which passes through a geometric center through which a longitudinal axis (50) of the jacket passes. Conductors (30--30) which are individually insulated are disposed adjacent to the longitudinal axis with each strength member being disposed between the conductors and the outer surface of the jacket.

Abstract: A cable (20) which is particularly suited to the transmission of substantially error-free data at relatively high rates over relatively long distances includes at least two pairs of individually insulated conductors (42--43). Each pair of individually insulated conductors is enclosed individually in its own tubular member (51) comprising a plastic material. A metallic shield (60) encloses the tubular members, and in a preferred embodiment, a plastic jacket (80) encloses the shield. In the preferred embodiment, two pairs of voice communications conductors are disposed at opposed locations between the shield and the jacket. The thickness of the tubular member is such that each insulated conductor of each twisted pair is caused to be spaced from the shield a distance which is not less than one half the diameter of the metallic wire portion of each pair enclosed by the tubular member.