Lucent Technologies Inc.

Fitel USA Corporation

Other

At+t Corp.

At&t Bell Laboratories

American Telephone & Telegraph Co., At&t Bell Laboratories

Furukawa Electric North America, Inc.

William Alfred Reed

Steven Eugene Golowich

David John DiGiovanni

Man Fei Yan

Mark J Schnitzer

Kenneth L Walker

Ashish Madhukar Vengsarkar

Per Bang Hansen

Andrew John Stentz

Lars Gruner-Nielsen

Sean L Jones

Albert John Ritger

Thomas Andrew Strasser

Jeffrey W Nicholson

Leonard G Cohen

Ian A White

Robert Scott Windeler

Paul Joseph Lemaire

Andrew Douglas Yablon

Jane Deborah LeGrange

David W Peckham

Alice Weimin Liu

David Kalish

Lars Erik Eskildsen

Clifford E Headley

John T Krause

Bera Palsdottir

Katherine Theresa Nelson

Gloria R Jacobovitz-Veselka

Jane B Clayton

Arthur F Judy

Jinendra Kumar Ranka

Andrew Ingles, Jr

Raymond Bradfield Kummer

Sunghee Yoon

Ming Yang

David Wayne Peckham

Bent Edvold

Peng Wang

Susanne Dyrbol

Lene V Jorgensen

Seo Y Park

Robert B Lee

Lucas Hsu

A GRIN fiber lens is fabricated by the steps of providing a graded index glass preform, thinning the graded index preform to remove a sufficient thickness of the graded glass to establish a desired &#x394;n, and drawing a graded index optical fiber from the thinned graded index preform. Thinning, in this context, refers to removal of graded index glass from the outside of the graded index preform so as to reduce its outer diameter. The thinning thus changes &#x394;n which is the refractive index difference between the center of the preform and its outer surface. The graded index preform can be provided by MCVD deposition followed by removal of the starting tube glass, by OVD deposition, by VAD, or by ion exchange fabrication. The thinned graded index preform is advantageously annealed before drawing in order to minimize ripple. And, in a variation of the process, an overcladding can be applied over the thinned graded preform before draw for further adjustment or control of the &#x394;n.

Method of fabricating graded-index optical fiber lenses

A system and technique for determining discontinuities over a span of a multimode optical fiber (MMF). An optical time domain reflectometer (OTDR) has an operating port, and a first end face of a singlemode optical fiber (SMF) is coupled to the operating port. Light pulses produced by the OTDR emerge from a second end face of the SMF, and an alignment stage aligns the second end face with an end face of a multimode optical fiber (MMF) having a core of given radius. The light pulses from the second end face of the SMF are applied at selected radial positions on the MMF core to excite corresponding mode groups in the MMF. Backscatter light produced by each excited mode group is coupled to the OTDR through the SMF. Locations and values of events detected along the MMF are indicated on the OTDR for each selected radial position.

Detection of discontinuities in a multimode optical fiber

A mode converter includes first and second optical waveguides and a GRIN fiber lens. The GRIN fiber lens is attached to both the first and the second waveguides.

Fiber devices using GRIN fiber lenses

A method for fabricating a GRIN fiber includes forming a tube of silica-glass having a tubular core and a concentric tubular cladding adjacent and external to the tubular core. The core has a dopant density with a radially graded profile. The method includes partially collapsing the tube by applying heat thereto. The partially collapsed tube has a central channel. The method includes passing a glass etchant through the central canal to remove an internal layer of silica glass, and then, collapsing the etched tube to a rod-like preform.

Method of fabricating a GRIN fiber

A technique for measuring the modal power distribution of an optical source (for example, a laser) launching pulses into a multimode fiber involves a characterization of the multimode fiber itself in terms of its differential modal delay. A reverse differential mode delay measurement is then performed to characterize the interaction of the optical source with the multimode fiber. By knowing these characteristics, the modal power distribution of the source into the fiber can then be determined by using a reconstruction algorithm.

Technique for measuring modal power distribution between an optical source and a multimode fiber

A dispersion compensating fiber and module are described for controlling residual dispersion in a dispersion compensated system. The dispersion compensating fiber is designed with dispersion curve having an inflection point at a wavelength near the optical transmission operating wavelength region. The dispersion curve, having an inflection point near the operating wavelength region, produces a relative dispersion slope that closely matches the relative dispersion slope of the transmission fiber over a relatively wide bandwidth surrounding the operating wavelength region.

Dispersion compensating module and fiber for control of residual dispersion

An optical system for monitoring or imaging a sample includes a probe, an optical splitter or circulator, and an optical detector. The probe includes an optical fiber and a GRIN fiber-size lens fused to one end of the fiber. The optical splitter or circulator receives light from a source and directs a portion of the received light to the fiber. The optical detector is coupled to receive a portion of light collected from the sample by the GRIN fiber-size lens and is configured determine a characteristic of the sample from the received light.

Grin-fiber lens based optical endoscopes

A dispersion compensation module (DCM) for compensating dispersion of an optical fiber transmission link is provided. The optical fiber transmission link comprises a transmission fiber and the DCM. The DCM comprises at least first and second dispersion compensating fibers, DCF and DCF , respectively. DCF and DCF each have a dispersion, D and D , respectively, a dispersion slope, S and S , respectively, and a relative dispersion slope, RDS and RDS , respectively. The transmission fiber also has a dispersion, D , a dispersion slope, S , and a relative dispersion slope, RDS . DCF and DCF are selected based on their respective relative dispersion slopes, RDS and RDS , respectively. DCF and DCF have particular, lengths, L and L , respectively. The DCFs are combined with each other and with the transmission fiber and RDS and RDS are such that the combination of the transmission fiber with the combined DCFs results in overall dispersion compensation of the optical fiber transmission link.

Method and apparatus for providing dispersion compensation

A transmission fiber for use in a Raman amplified optical communication system is formed to exhibit certain characteristics that limit modulation instability and four-wave mixing in the amplification region, thus reducing the noise component present in the transmission system. In particular, the group-velocity dispersion (denoted as D and measured in terms of ps/nm-km) is restricted to be either non-positive or greater than &plus;1.5 ps/nm-km in the pump wavelength range of interest (a typical pump wavelength range being 1430-1465 nm). Preferably, the magnitude of the dispersion is kept below a value of 10 ps/nm-km in the signal wavelength range of interest (e.g., the &ldquo;C&rdquo; band or &ldquo;L&rdquo; band). Four-wave mixing is reduced by ensuring that the zero-dispersion frequency of the transmission fiber is not centered between the pump frequency and a frequency experiencing Raman gain.

Raman amplified optical system with reduction of four-wave mixing effects

A GRIN fiber lens has a silica-glass core whose refractive index has a radial profile. The profile has a radial second derivative whose average magnitude in the core is less than about 1.7&times;10 microns times the value of the refractive index on the axis of the GRIN fiber lens.

GRIN fiber lenses

Our method of making high bandwidth silica-based multimode optical fiber comprises provision of a non-circular preform, and drawing fiber of chiral structure from the preform. The non-circular preform can be made by maintaining the inside of the tubular preform under reduced pressure during at least part of the collapse, resulting in a non-circular core and cladding. It can also be made by removal (e.g., by grinding or plasma etching) of appropriate portions of the preform, resulting in a circular core and non-circular cladding. In the latter case, fiber is drawn at a relatively high temperature such that, due to surface tension, the cladding assumes substantially circular shape and the core assumes a non-circular shape. The chiral structure is imposed on the fiber in any appropriate way, e.g., by twisting during fiber drawing the fiber alternately in clockwise and couterclockwise sense relative to the preform.

Method of making an improved multimode optical fiber and fiber made by method

A Raman amplified dispersion compensation module has a first dispersion compensating fiber (DCF) with an input end and an output end. The first DCF has a known Raman gain coefficient (g (&lgr;)), Raman effective fiber area (A ), and dispersion characteristic. An input end of a second DCF is arranged to receive light signals from the output end of the first DCF. The second DCF has a known gain coefficient and effective area, and a dispersion characteristic selected to cooperate with that of the first DCF to produce a desired total module dispersion. The lengths of the DCFs are selected in a manner that optimizes the overall module gain.

Raman amplified dispersion compensating modules

Disclosed is a method of launching a light beam from a semiconductor laser into a multimode optical fiber, as well as apparatus for launching the light beam. The light beam is directed at nominally the center of the input face of the multimode fiber such that the (unguided) light beam makes an angle &thgr; (typically in the range 1-20 degrees) with the direction perpendicular to the input face of the multimode fiber. The angle &thgr; is selected such that at least one lower order mode of the guided radiation in the multimode fiber is substantially not excited in the fiber, with at least some higher order modes being substantially excited. Several specific embodiments are disclosed.

Article comprising means for mode-selective launch into a multimode optical fiber, and method for a mode-selective launch

Embodiments of the invention include an optical communications system including one or more optical transmission devices, one or more optical receiving devices, and at least one positive dispersion optical fiber coupled therebetween. The fiber includes a doped core region with an index of refraction n , a cladding region with an index of refraction n , and first and second annular rings or regions therebetween with indices of refraction n and n , respectively. The various regions are manufactured in such a way that the refractive index value ranges are: 0.14<(n &minus;n )/n <0.31, &minus;0.19<(n &minus;n )/n <&minus;0.02, and &minus;0.20<(n &minus;n )/n <&minus;0.08. The fibers exhibit a chromatic dispersion greater than 20&plusmn;2.0 ps/(nm-km) and a dispersion slope less than 0.062 ps/(nm -km) at a wavelength of 1550 nm. Also, the fibers have a relatively large effective core area, A , e.g., greater than 100.0 &mgr;m , and a relative dispersion slope (RDS) less than 0.0032 nm . The mode field diameter (MFD) is at least 11.9&plusmn;0.7 &mgr;m. These desirable transmission characteristics are achieved without many of the manufacturing and economic limitations of conventional fibers.

Positive dispersion optical fiber having large effective area

Growing community of inventors

Summit, NJ, United States of America

William Alfred Reed