Methods for modifying ovality of optical fiber preforms

Abstract

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.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] The present application is a divisional of co-pending U.S. application Ser. No. 10 / 430,779, filed May 5, 2003, entitled “Methods for Modifying Ovality of Optical Fiber Preforms,” the disclosure of which is entirely incorporated by reference herein.FIELD OF THE INVENTION [0002] The present invention relates generally to optical fiber fabrication, and more specifically, to methods for reducing the ovality of optical fiber preforms used in manufacturing optical fiber. BACKGROUND OF THE INVENTION [0003] Communications and data transmission systems that transmit information signals in the form of optical pulses over optical fiber are now commonplace, and optical fibers have become the physical transport medium of choice in long distance telephone, data and video communication networks due to their signal transmission capabilities, which greatly exceed those of mechanical conductors. Despite their advantages, however, difficulties in their ma...

AI Technical Summary

Benefits of technology

"The present invention provides methods for reducing the ovality of optical fiber preforms during the creation process. The methods include etching the starting tube or core rod to reduce its ovality. The etching can be done by heating the tube or core rod and using a plasma torch. The ovality of the starting tube or core rod can be measured before etching. The methods also include rotating the starting tube or core rod to further reduce its ovality. The invention aims to reduce the PMD (polarization mode dispersion) of optical fibers drawn from the optical fiber preform."

Problems solved by technology

Despite their advantages, however, difficulties in their manufacture must be overcome in order for lengthy, high-yield and error-free optical fiber to be produced in mass.

Although the generation of preforms by the method described above are commonly utilized in optical fiber manufacturing, preforms generated by this process often suffer from ovality; that is, the preforms do not necessarily have a circular cross section throughout their entire length.

Preform ovality is undesirable because it changes and more often increases the Polarization Mode Dispersion (PMD) of optical fiber.

PMD limits the transmission capacity of optical communication systems by creating inter-symbol interference.

Images