Fitel USA Corporation

Zhi Zhou

Harry Douglas Garner, Jr

Siu-Ping Hong

Alan H McCurdy

James William Fleming

David Kalish

Jinkee Kim

Thomas John Miller

Albert John Ritger

Paul Francis Glodis

Jason W Shiroishi

Andrew Ingles, Jr

Haiying Huang

Shunhe Xiong

William H Sleigher, Jr

Gene Kent Weeks

Christopher Timothy Gallagher

Stephen Mast

John F Ryan, Iii

John Popwell

Methods for modifying preform core ovality during and subsequent to the formation of an optical fiber preform. After MCVD deposition forms the core rod, but prior to overcladding of the core rod, the code rod may be etched to change its ovality. In order to etch the core rod, the core rod may be mounted to lathe, rotated by at least two rotors, and subjected to a heat source. Additionally, one of the at least two rotors may be phase-shifted from another one of the at least two rotors after the core rod is mounted on the lathe.

Methods for modifying ovality of optical fiber preforms

Methods and apparatuses negate a measured mechanical twist of an optical fiber by introducing a counteracting twist to bring the net mechanical twist closer to zero, which reduces the fiber's polarization mode dispersion (PMD). A spool of optical fiber having undesirable mechanical twist is mounted and fiber is drawn from the end of the spool to impart a specified counteracting mechanical twist. Additionally, the spool may be controllably rotated by a control system while optical fiber is drawn there from, allowing the system to generate a precise amount of counteracting mechanical twist in the fiber.

Methods and apparatuses for correcting mechanical twist in optical fiber

A method and an apparatus for obtaining measurements of eccentricity in optical fibers, from which the spin imparted to the optical fiber can be ascertained. The method and apparatus enable eccentricity to be measured in such a way that this measurement can be utilized to determine the amount of spin imparted to an optical fiber as the optical fiber was being drawn, although the eccentricity measurement may be used for purposes other than to determine the amount of spin in the fiber. By viewing the fiber from one or more positions along the length of the fiber, the eccentricity of the fiber as a function of position along the length of the fiber can be determined. The amount of spin in the fiber can then be determined from the eccentricity measurement.

Method and apparatus for measuring eccentricity in a optical fiber

A system and method is disclosed for manufacturing single mode optical fiber which incorporates a spin in the molten fiber during manufacturing. The introduction of spin minimizes a form of distortion called polarization mode dispersion (PMD) and varying the spin, i.e. changing its characteristics, is known to further reduce PMD. However, introducing spin on a molten fiber may result in also introducing twist on the fiber. Twist is a non-permanent rotational force on the cooled fiber which causes stress and is to be avoided. A spin function is disclosed that not only contains a high degree of variability for reducing PMD, but also ensures that mechanical twist on the fiber is minimized, thus reducing stress on the fiber. The spin function modulates either the amplitude, frequency, or both, at the beginning of a cycle to minimize twist on the fiber.

Systems and methods for forming ultra-low PMD optical fiber using amplitude and frequency keyed fiber spin functions

A system and method is disclosed for determining information regarding the result of introducing a rotational force on an optical fiber during manufacturing. A rotational deformation of the molten fiber, called spin, is imparted that becomes permanent upon cooling of the fiber. The rotational force also introduces twist on the cooled fiber, which is a non-permanent, mechanical rotation of the fiber. The system and method uses a diameter measuring device that produces a signal corresponding to the fiber's diameter with respect to time. Since the fiber is slightly elliptical in practice, periodic variations in the diameter measurement signal are detected that reflect the rotation imparted into the fiber. The signal is further processed to provide data regarding the effect of the rotations introduced into the fiber, namely the twist and spin present in the fiber.

System and method for obtaining spin and mechanical twist data during optical fiber draw

A precision method is defined for identifying defective sections of a spoolable material for removal. Defective sections are noted during manufacture and the spool containing the material is subsequently unwound to allow removal of the defective sections. The invention uses rotation data corresponding to the location on the spool where the fiber contains defects. A process controller records rotational positioning data from the take-up spool during manufacturing and uses the information to locate the defect when unwinding the spool. In addition, the pitch of winding the fiber onto the spool may be altered during manufacturing to indicate the beginning and end of a defective section. In this instance, the defective portion of the fiber can be determined during unwinding by monitoring the pitch width of the material. Finally, an algorithm for defining cut out bands adjacent to the defective sections aid in ensuring that no remaining defective fiber remains.

Systems and methods for precision mapping and removal of defects in a spooled material using spool rotation and variable winding pitch

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Lawrenceville, GA, United States of America

Zhi Zhou