Jeffrey P Nicholson

US Patent:

6504973, Jan 7, 2003

Filed:

Mar 16, 2002

Appl. No.:

10/099820

Inventors:

David J. DiGiovanni - Montclair NJ
William Alfred Reed - Summit NJ
Jeffrey W. Nicholson - Chatham NJ
Man Fei Yan - Berkeley Heights NJ
Bera Palsdottir - Copenhagen, DK

Assignee:

Fitel USA Corp. - Norcross GA

International Classification:

G02B 626

US Classification:

385 27, 385123, 359160, 359334, 372 6

Abstract:

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 ()), 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.

US Patent:

6775447, Aug 10, 2004

Filed:

Sep 20, 2002

Appl. No.:

10/251464

Inventors:

Jeffrey W. Nicholson - Chatham NJ
Man Fei Yan - Berkeley Heights NJ

Assignee:

Fitel USA Corp. - Norcross GA

International Classification:

G02B 600

US Classification:

385122, 385123, 372 21

Abstract:

An optical fiber suitable for generation of a supercontinuum spectrum when light pulses of femtosecond (10 sec. ) duration are launched at a certain wavelength into the fiber. The fiber includes a number of sections of highly non-linear fiber (HNLF) wherein each section exhibits a different dispersion at the wavelength of the launched light pulses. The fiber sections are joined, for example, by fusion splicing the sections in series with one another so that the dispersions of the sections decrease from an input end to an output end of the fiber. In the disclosed embodiment, a low noise, coherent supercontinuum spanning more than one octave is generated at the output end of the fiber when pulses of light of 188 fs duration are launched into the fiber at a repetition rate of 33 MHz and with an energy of three nanojoules per pulse.

US Patent:

6967767, Nov 22, 2005

Filed:

Mar 18, 2003

Appl. No.:

10/390859

Inventors:

Jeffrey W. Nicholson - Chatham NJ, US

Assignee:

Fitel USA Corp - Norcross GA

International Classification:

H01S003/00
H04B010/12

US Classification:

359334, 3593413

Abstract:

A swept wavelength source for broad bandwidth Raman pump applications includes a source of ultrashort (e. g. , picosecond) optical pulses. The pulse train output from the source is then applied as an input to a linear dispersive element (such as a section of negative dispersion-shifting fiber) which functions to “stretch” the ultrashort pulses, causing the pulses to become separated in time, with a continuous shift in the wavelength through the length of the pulse.

US Patent:

6990270, Jan 24, 2006

Filed:

Feb 11, 2004

Appl. No.:

10/776432

Inventors:

Jeffrey Nicholson - Chatham NJ, US

Assignee:

Fitel U.S.A. Corp. - Norcross GA

International Classification:

G02B 6/00
G02B 6/26

US Classification:

385 27, 372 6, 398 42

Abstract:

A source of high-power femtosecond optical pulses comprises a combination of a relatively short rare-earth doped fiber amplifier (e. g. , less than five meters) with a first section of single mode fiber (or other dispersive element) disposed at the input of the amplifier to “pre-chirp” the output from a femtosecond pulse source, and a second section of single mode fiber fused to the output of the fiber amplifier to provide compression to the amplified pulses generated by the fiber amplifier. The rare-earth doped fiber amplifier is formed to comprise a normal dispersion, which when combined with self-phase modulation and distributed gain leads to a regime in amplifiers defined as “self-similar propagation”. In this regime of operation, the fiber amplifier generates high energy pulses with a parabolic shape (the parabolic shape defined as a function of time). These pulses also exhibit a strong linear chirp, where the linear nature of the chirp leads to efficient compression of the pulses.

US Patent:

7171089, Jan 30, 2007

Filed:

Feb 22, 2005

Appl. No.:

11/063406

Inventors:

Kenneth S. Feder - Murray Hill NJ, US
Jeffrey W. Nicholson - Chatham NJ, US
Paul S. Westbrook - Bridgewater NJ, US

Assignee:

Fitel USA Corp. - Norcross GA

International Classification:

G02B 6/00
H04J 14/02
H01S 3/10

US Classification:

385122, 385123, 385 28, 398 81, 398148, 372 21

Abstract:

Enhancement of the supercontinuum generation performance of a highly-nonlinear optical fiber (HNLF) is accomplished by performing at least one post-processing treatment on the HNLF. Particularly, UV exposure of the HNLF will modify its dispersion and effective area characteristics so as to increase its supercontinuum bandwidth, without resorting to techniques such as tapering or introducing unwanted reflections into the HNLF. The UV exposure can be uniform, slowly varying or aperiodic along the length of the HNLF, where the radiation will modify the nonlinear properties of the HNLF. Various other methods of altering these properties may be used. The output from the HNLF can be monitored and used to control the post-processing operation in order to achieve a set of desired features in the enhanced supercontinuum spectrum.

US Patent:

7228029, Jun 5, 2007

Filed:

Sep 20, 2005

Appl. No.:

11/230905

Inventors:

Siddharth Ramachandran - Hoboken NJ, US
Jeffrey Nicholson - Chatham NJ, US

Assignee:

Furukawa Electric North America Inc. - Norcross GA

International Classification:

G02B 6/26
G02B 6/02
H01S 3/30

US Classification:

385 28, 385 27, 385123, 385127, 372 6

Abstract:

The specification describes an optical fiber device for propagating and recompressing high energy, ultrashort pulses with minimal distortions due to nonlinearity. The device is based on propagation in a higher order mode (HOM) of a few-moded fiber. Coupling into the HOM may be accomplished using long-period gratings. Features of the HOM fiber mode that are useful for high quality pulse compression include large effective area, high dispersion and low dispersion slope. In a preferred case the long period gratings go through a turn-around point (TAP) at the wavelength of operation.

US Patent:

7535934, May 19, 2009

Filed:

Mar 23, 2007

Appl. No.:

11/728226

Inventors:

Jeffrey W. Nicholson - Morristown NJ, US
Paul S. Westbrook - Bridgewater NJ, US

Assignee:

OFS Fitel LLC - Norcross GA

International Classification:

H01S 3/30

US Classification:

372 6, 372 64, 372 5011

Abstract:

An optical continuum source is formed that is used to generate both a continuum and one or more light peaks outside the bandwidth of the continuum. In particular, one or more fiber Bragg gratings exhibiting a resonant wavelength less than the short wavelength edge (or greater than the long wavelength edge) of a predetermined continuum are inscribed into a section of highly nonlinear fiber (HNLF) and used to generate the additional light peaks. Gratings may also be formed for areas along the fiber where the continuum spectral power density is essentially “zero”. It has been discovered that the use of a Bragg grating generates phase matching with the propagating optical signal, thus resulting in the creation of the additional peaks.

US Patent:

7817258, Oct 19, 2010

Filed:

Jun 20, 2008

Appl. No.:

12/214629

Inventors:

Poul Kristensen - Valby, DK
Jeffrey W. Nicholson - Morristown NJ, US
Siddharth Ramachandran - Hoboken NJ, US
Andrew D. Yablon - Livingston NJ, US

Assignee:

OFS Fitel LLC - Norcross GA

International Classification:

G01N 21/00

US Classification:

356 731

Abstract:

The output modal content of optical fibers that contain more than one spatial mode may be analyzed and quantified by measuring interference between co-propagating modes in the optical fiber. By spatially resolving the interference, an image of the spatial beat pattern between two modes may be constructed, thereby providing information about the modes supported by the optical fiber.