Fitel USA Corporation

Ofs Fitel, LLC

Alan H McCurdy

Harry Douglas Garner, Jr

Zhi Zhou

Lars Gruner-Nielsen

David W Peckham

Jinkee Kim

Robert L Lingle

Siu-Ping Hong

Abhijit Sengupta

Gene Kent Weeks

Stephen Mast

John F Ryan, Iii

Torger Tokle

John Popwell

A few-mode optical fiber comprises a core surrounded by a cladding, having a step index profile that is structured to support propagation of a plurality of desired signal-carrying modes, while suppressing undesired modes. The core and cladding are configured such that the undesired modes have respective effective indices that are close to, or less than, the cladding index such that the undesired modes are leaky modes. The index spacing between the desired mode having the lowest effective index and the leaky mode with the highest effective index is sufficiently large so as to substantially prevent coupling therebetween.

Step-index few-mode fiber designs for spatial multiplexing

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 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

Systems and methods are disclosed for measuring Polarization Mode Dispersion (PMD) of single-mode optical fiber. The method allows for a faster and easier method of accurately measuring intrinsic ultra low PMD optical fiber in a low mode coupling state. The method involves the introduction of a plurality of localized external perturbations on the optical fiber, after which the optical fiber is allowed to reach a steady state, and then measurement of the differential group delay occurs using standard measurement techniques. The plurality of localized external perturbations is altered followed by another measurement of the differential group delay. After obtaining a sufficient number of measurements to provide a Maxwellian distribution, the Polarization Mode Dispersion value can be calculated as the average of the distribution.

Systems and methods for accurately measuring low values of polarization mode dispersion in an optical fiber using localized external perturbation induced low mode coupling

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Fulton County, GA, United States of America

Alan H McCurdy