International Telephone and Telegraph Corporation

Charles K Kao

Mokhtar S Maklad

James E Goell

Peter D Steensma

Gary W Bickel

Lozure Gene Wolfgang

An effective graded index profile optical fiber waveguide comprises alternating regions of high and low indexes of refraction of controlled thickness. The effective refractive index of the fiber has a graded profile of decreasing refractive index when the regions of high index have either a constant or decreasing thickness and the low index regions increase outwardly from the center. The effective refractive index has a particular graded profile of refractive index when the thicknesses of the regions of low refractive index and the high refractive index are appropriately chosen.

Optical fiber waveguide with effective refractive index profile

High-strength optical preforms and optical fibers, particularly useful in light-wave communication systems, are fabricated by techniques producing high surface compressive forces in thin outer layers. These result in substantially increased fiber tensile strength, durability, and fiber life. High surface stresses are achieved in three-layer and four-layer preforms and fibers by employing particular combinations of core, cladding, and layer compositions, dopants, coefficients of thermal expansion, and glass transition temperatures. Various suitable manufacturing methods are disclosed using chemical vapor deposition techniques. For example, preforms may be fabricated by external deposition of layers on a drawn core-glass rod, or by internal CVD methods in which layers are sequentially deposited within hollow tubular silica substrates that are then collapsed into solid preforms by known techniques. In the internal deposition methods, preform finishing techniques are also disclosed for removing excess substrate material so as to leave a high-strength compressive layer of substantially pure silica.

High-strength optical preforms and fibers with thin, high-compression

A first optical fiber end is precisely aligned in the interstice between a plurality of relatively equal diameter cylindrical rods. The rods are of disparate lengths and the fiber as located in the interstice has its tip accurately aligned with respect to a reference surface of one of the rods. The alignment of the fiber in this manner permits a similar rod arrangement to interlock with the above described structure to enable a similarly supported fiber to be accurately positioned with respect to the first fiber due to the interlocking of the respective rod assemblies.

Interlocking precision optical fiber connector or support

Optical communication fibers having improved fatigue resistance are provided by encapsulating the fibers in a water impervious material. The water impervious material prevents the interaction of water with glass along the fiber outer surface and prolongs the operational life-time of the fibers.

Water resistant high strength fibers

A simple mechanical connector for joining plastic coated optical fibers provides means for stripping the plastic from the fibers and for automatically aligning the fiber cores. The connector houses three equidistantly spaced teeth protruding from the inner surface of the connector. Inserting a plastic coated fiber within the connector causes the plastic material to be displaced by the teeth and causes the fiber to become precisely centered within the connector. When the connector contains teeth members at both ends of the connector a pair of optical fibers can become automatically aligned by inserting one of the fibers into each end of the connector.

Self centering connector design

Methods and materials are disclosed for providing an optical fiber transmission mixer wherein the cladding material is removed from an intermediate region of a plurality of fibers and the exposed fiber cores are encapsulated in a matching or slightly higher refractive index material. The encapsulated intermediate region of the fibers is then enclosed in a low index sheath to prevent light from escaping from the mixer.

Optical fiber transmission mixer and method of making same

A method and means is disclosed for continuously monitoring an optical fiber's attenuation or loss as it is being formed, which includes: a light source, which may be the heated fiber itself during drawing operations or an external source; passing the light through the fiber being produced; positioning the end of the fiber in a holder adjacent to a light detector, for example a photodiode with or without passing the transmitted light through a filter; detecting the light transmitted by the fiber from the light source; converting the detected light into an electrical equivalent signal; amplifying the signal if necessary and recording or observing the changes in the signal to determine an objective measure of the optical fiber's attenuating characteristic.

Method for using on line optic fiber loss monitor

The dispersion effects in an optical fiber transmission line are equalized by producing a predetermined delay characteristic for each wavelength of an optical beam having a finite bandwidth which is the inverse of a given delay characteristic for each optical wavelength propagated through the transmission line. This is accomplished by launching shorter wavelength components of the optical beam at low angles with respect to the axis of the transmission line into the transmission line and launching longer wavelength components at high angles with respect to the axis of the transmission line into the transmission line. Two arrangements are disclosed to accomplish the above-mentioned launching technique. One arrangement includes a time of flight dependent annularly ruled transmission grating and the other arrangement includes passing a time of flight dependent moving acoustic wave through the optical beam.

Method and arrangements for dispersion equalization of optical fiber

A continuous optical fiber manufacturing process utilizes the method of chemical vapor deposition of the glass forming materials within an R.F. excited glow discharge. The rapid deposition rate within the discharge provides a sufficient stream of glass material for winding into a finished fiber on a synchronous take-up mechanism. Alternate embodiments include an oxygen air stream to remove dust particles from the fiber surface and an in-line fluorine stream to terminate surface bonding and reduce moisture attack on fiber surfaces.

Continuous process for manufacturing optical fibers

Methods and apparatus are disclosed for forming a precision three-dimensional surface to clad optical fibers. One embodiment provides means for deforming the fiber end to conform to the geometry of the interstice formed between three tangential and parallel cylinders. The precision three-dimensional fiber end enables accurate low loss coupling between the fibers to be achieved through the accurate reference planes presented.

Precision surface optical fibers

Optical fiber ends are precisely aligned and coupled together in the interstice between a plurality of like contacting cylindrical rods. The rods are mounted along and around the fibers within an adjustable connector assembly. Means are provided for expanding the interstice to inset the fiber ends and for clamping the rods in position around the fibers. A plurality of connectors may be used to align a number of optical fibers enclosed in a common cable or bundle.

Precision optical fiber connector

A multiple access fiber optical bus system having superior features as compared to the prior art is provided in which single fibers may be used as transmission lines in a closed loop system. A plurality of optical transmission mixers are provided, each of which mixes the inputs from one or more transmission lines to provide outputs to a multiplicity of transmission lines. Each of the mixers independently operates a plurality of transmission lines. Various degrees of reliability terminals are provided. A high reliability terminal has inputs from and outputs to the last one of the transmission lines on the output side of each of the independent mixers. A low reliability terminal has connections to only one of the independent mixers transmission lines. Any degree of reliability between the lowest and highest can be obtained depending upon the number of independent mixer loops to which such a terminal is connected.

Growing community of inventors

Roanoke, VA, United States of America

Charles K Kao