Abstract: The presence of (typically unintended) birefringence in single mode optical fiber can severely limit the usefulness of the fiber for, e.g., high bit rate or analog optical fiber communication systems, due to the resulting polarization mode dispersion (PMD). It has now been discovered that PMD can be substantially reduced if, during drawing of the fiber, a torque is applied to the fiber such that a "spin" is impressed on the fiber. Desirably the torque is applied such that the spin impressed on the fiber does not have constant spatial frequency, e.g., has alternately clockwise and counterclockwise helicity. At least a portion of optical fiber according to the invention has spin alternately clockwise and counterclockwise.

Abstract: The presence of (typically unintended) birefringence in single mode optical fiber can severely limit the usefulness of the fiber for, e.g., high bit rate or analog optical fiber communication systems, due to the resulting polarization mode dispersion (PMD). It has now been discovered that PMD can be substantially reduced if, during drawing of the fiber, a torque is applied to the fiber such that a "spin" is impressed on the fiber. Desirably the torque is applied such that the spin impressed on the fiber does not have constant spatial frequency, e.g., has alternately clockwise and counterclockwise helicity. At least a portion of optical fiber according to the invention has a spin whose spatial frequency exceeds 4 spins/meter.

Abstract: This invention is a process of contactless monitoring the tension in a moving fiber, such as during the process of drawing optical fibers from preforms, and a non-contacting tension gauge which allows measurement of fiber tension at line speed. The device can be used to monitor the tension during the run without any adverse effects on fiber performance. The measurement may be steady, intermittent or sinusoidal as appropriate. The process includes the steps of sensing an initial position of a moving optical fiber, applying a gas jet onto a section of the optical fiber in a direction transverse to the direction of movement of the fiber so as to cause deflection of the moving fiber axially of the gas jet, sensing the magnitude of deflection of the fiber relative to the said initial position, and, depending on the magnitude of deflection, adjusting the tension in the fiber so as to cause the change in the magnitude of deflection to a preselected value.

Abstract: The speed at which optical fibers can be drawn and coated is significantly increased by efficiently stripping the gas boundary layer entrained by the moving fiber. The stripping is periodically repeated to ensure that the entrained flow is not re-established.

Abstract: A method of coating uncoated portions of a coated optical fiber is disclosed. In this method a grooved split mold apparatus is used. This fiber, including coated portions of the fiber are placed within the groove and appropriately tensioned so as to prevent contact between the uncoated portions of the fiber and the mold. Injection molding techniques are then used to recoat the uncoated portions of the fiber.

Abstract: The specification describes techniques for coating fiber waveguides by passing the fiber through a reservoir of coating material while preventing the gross accumulation of bubbles in the reservoir. Preventing accumulation of bubbles improves coating concentricity and quality.