Patents by Inventor Jeffrey W. Nicholson
Jeffrey W. Nicholson has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 8111386Abstract: 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. Measurements of the phase front exiting the optical fiber under test are advantageously performed in the far field.Type: GrantFiled: May 12, 2009Date of Patent: February 7, 2012Assignee: OFS Fitel, LLCInventors: Jeffrey W. Nicholson, Andrew D. Yablon
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Patent number: 8023179Abstract: In accordance with the present invention, a bulk optic material (for example, silica) is processed to form a spatially microstructured element, such as a photonic bandgap (PBG) structure. An ultra-short laser pulse source is used as an input signal that is applied to the bulk optic PBG structure to generate an enhanced continuum output. The PBG structure may comprise any type of one-, two- or three-dimensional grating structure, where the selected structure will dictate the type(s) of enhancement(s) that are present in the generated continuum—generally in the form of a broadened continuum and/or the inclusion of one or peaks in the continuum. The use of a relatively small-dimensioned bulk material allows for the continuum to be generated without the need for any type of optical confinement (waveguide). In one embodiment, the bulk PBG structure may be is subjected to one or more additional processes (such as UV exposure, electromagnetic field application, etc.Type: GrantFiled: March 15, 2007Date of Patent: September 20, 2011Assignee: OFS Fitel LLCInventors: Jeffrey W. Nicholson, Paul S. Westbrook
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Publication number: 20110210269Abstract: Methods and systems are described using a non-linear optical system comprising a laser and a light delivery system comprising a single mode fiber, a mode converter, and a high order mode fiber, wherein the light delivery system that receives light from the source and provides a structured free-space beam having an embedded Gaussian beam. The light delivery system functions to illuminate a region of a sample and generate a non-linear response in a spatial region smaller than that associated with a Gaussian beam having a width comparable to the width of the embedded Gaussian beam. In another aspect, the light delivery system illuminates a region of a sample and generates a non-linear emission of radiation, is depicted. A further aspect of this embodiment includes an imaging assembly for detecting the non-linear emission and using a signal derived from the detected emission to generate a microscopic image of the sample.Type: ApplicationFiled: November 24, 2010Publication date: September 1, 2011Applicant: OFS Fitel, LLCInventors: Jeffrey W. Nicholson, Siddharth Ramachandran
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Patent number: 7957619Abstract: An all-fiber optical pulse compression arrangement comprises a concatenated arrangement of a section of input fiber (e.g., a single mode fiber), a graded-index (GRIN) fiber lens and a section of pulse-compressing fiber (e.g., LMA fiber). The GRIN fiber lens is used to provide mode matching between the input fiber (supporting the propagation of chirped optical pulses) and the pulse-compressing fiber, with efficient pulse compression occurring along the length of the LMA fiber. The dispersion and length of the LMA fiber section are selected to provide the desired degree of pulse compression; for example, capable of reconstituting a femtosecond pulse as is used in supercontinuum generation systems.Type: GrantFiled: October 26, 2010Date of Patent: June 7, 2011Assignee: OFS Fitel, LLCInventors: Jeffrey W. Nicholson, Andrew D. Yablon
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Patent number: 7949215Abstract: A fiber laser having at least one pair of reflectors coupled to an optical fiber, the at least one pair of reflectors defining an optical cavity between the at least one pair of reflectors and being configured to reflect light within the optical cavity. At least one light pump is coupled to the optical fiber and configured to provide pump light into the optical cavity, and at least one medium is positioned within the optical cavity and configured to generate signal light from the pump light in the optical cavity. Further, at least one grating positioned within the optical cavity and configured to couple the signal light out of the optical cavity.Type: GrantFiled: April 18, 2008Date of Patent: May 24, 2011Assignee: OFS Fitel, LLCInventors: Jeffrey W. Nicholson, Paul S. Westbrook
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Patent number: 7940816Abstract: A polarization-maintaining figure eight (PMFE) fiber laser is configured to generate ultrashort (femtosecond) output pulses by intentionally inserting asymmetry (in the form of a phase bias) into the bi-directional loop of the fiber laser. The introduction of asymmetry (via an asymmetric coupler, splice, attenuator, fiber bend, multiple amplifying sections, or the like) allows for an accumulation of phase difference within the bi-directional loop sufficient to create modelocking and generate ultrashort output pulses.Type: GrantFiled: September 5, 2008Date of Patent: May 10, 2011Assignee: OFS Fitel LLCInventor: Jeffrey W. Nicholson
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Publication number: 20110058769Abstract: An all-fiber optical pulse compression arrangement comprises a concatenated arrangement of a section of input fiber (e.g., a single mode fiber), a graded-index (GRIN) fiber lens and a section of pulse-compressing fiber (e.g., LMA fiber). The GRIN fiber lens is used to provide mode matching between the input fiber (supporting the propagation of chirped optical pulses) and the pulse-compressing fiber, with efficient pulse compression occurring along the length of the LMA fiber. The dispersion and length of the LMA fiber section are selected to provide the desired degree of pulse compression; for example, capable of reconstituting a femtosecond pulse as is used in supercontinuum generation systems.Type: ApplicationFiled: October 26, 2010Publication date: March 10, 2011Applicant: OFS FITEL, LLCInventors: Jeffrey W. Nicholson, Andrew D. Yablon
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Publication number: 20110052197Abstract: An arrangement for providing pulse compression at the output of an optical continuum source (advantageously used in spectral slicing applications) includes a section of higher-order mode (HOM) fiber configured to exhibit a predetermined dispersion in at least a portion of the predetermined wavelength range and an effective area greater than 40 ?m2, the dispersion of the HOM fiber selected to compensate for the dispersion introduced by the optical continuum source. The HOM fiber generates a compressed pulse output therefrom. An input mode converter is used to convert the created continuum from the fundamental mode associated with the conventional continuum sources to the higher-order mode(s) supported by the HOM fiber used to perform pulse compression. A bandpass filter is used to limit the bandwidth of the continuum signal to that associated with both the efficient conversion range of the mode converter and desired dispersion characteristic of the HOM fiber.Type: ApplicationFiled: August 31, 2009Publication date: March 3, 2011Inventors: Jeffrey W. Nicholson, Siddharth Ramachandran
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Patent number: 7881620Abstract: An arrangement for generating beat notes with a relatively high signal-to-noise ratio (SNR) utilizes a pulsed laser source coupled into a section of post-processed highly-nonlinear optical fiber (HNLF) to generate a frequency comb having one or more regions of enhanced spectral power. A second laser signal source is overlapped with the frequency comb to form one or more “beat notes” at difference frequencies(y) between the second source and the continuum comb. By virtue of the post-processing, areas of spectral enhancement are formed along the comb, and are positioned to interact with the second laser signal to generate optical beat notes. The second laser signal may be from an external source (forming beat notes from a signal “outside” of the comb), or may be a frequency-multiplied version of the generated supercontinuum (forming beat notes from a signal “within” the comb).Type: GrantFiled: May 3, 2006Date of Patent: February 1, 2011Assignee: OFS Fitel, LLCInventors: Jeffrey W. Nicholson, Paul S. Westbrook
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Patent number: 7844146Abstract: An all-fiber optical pulse compression arrangement comprises a concatenated arrangement of a section of input fiber (e.g., a single mode fiber), a graded-index (GRIN) fiber lens and a section of pulse-compressing fiber (e.g., LMA fiber). The GRIN fiber lens is used to provide mode matching between the input fiber (supporting the propagation of chirped optical pulses) and the pulse-compressing fiber, with efficient pulse compression occurring along the length of the LMA fiber. The dispersion and length of the LMA fiber section are selected to provide the desired degree of pulse compression; for example, capable of reconstituting a femtosecond pulse as is used in supercontinuum generation systems.Type: GrantFiled: April 30, 2008Date of Patent: November 30, 2010Assignee: OFS Fitel, LLCInventors: Jeffrey W. Nicholson, Andrew D. Yablon
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Publication number: 20100296527Abstract: A passively modelocked fiber laser utilizes a rare-earth-doped fiber section as the gain medium, which exhibits a relatively high absorption (e.g., peak pump absorption >50 dB/m) and relatively low dispersion (e.g., ?20 ps/km-nm<Dg<0). Passive modelocking is provided by a single-walled carbon nanotube (SWNT) saturable absorber, formed on endface portions of a section of un-doped fiber. The remaining components (input/output couplers, isolator) are preferably integrated into a single component and coupled to the un-doped optical fiber. This combination yields a laser cavity with a slightly anomalous overall dispersion, preferred for soliton generation and creating optical pulses with a sub-picosecond pulse width and repetition frequency over 100 MHz.Type: ApplicationFiled: May 19, 2009Publication date: November 25, 2010Inventor: Jeffrey W. Nicholson
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Publication number: 20100290106Abstract: A light generation and amplification system includes a length of laser-active filter fiber having a refractive index profile that suppresses unwanted Stokes orders at wavelengths longer than a target wavelength and that has normal dispersion over its operating wavelength. A nested series of reflectors is provided at the fiber's input and output ends, and are configured to provide a nested series of Raman cavities, separated in wavelength by approximately the respective Stokes shifts. The first cavity in the series is a combined cavity that provides laser oscillation due to a combination of ionic gain and feedback at a selected first wavelength and that provides Raman gain to light at the first Stokes shift of the first wavelength when light at the first wavelength has an energy exceeding a Raman scattering threshold. The Raman cavities provide a stepwise transition between the first wavelength and the target wavelength.Type: ApplicationFiled: May 11, 2010Publication date: November 18, 2010Applicant: OFS Fitel LLC, a Delaware Limited Liability CompanyInventors: David J. DiGiovanni, Clifford E. Headley, Jeffrey W. Nicholson, Man F. Yan
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Publication number: 20100284659Abstract: An optical waveguide has a refractive index variation that is structured to provide the fiber, over a wavelength operating range, with an effective area supporting multiple Stokes shifts and with a negative dispersion value at a target wavelength within the wavelength operating range. The refractive index variation is further structured to provide the fiber with a finite LP01 cutoff at a wavelength longer than the target wavelength, whereby the LP01 cutoff wavelength provides a disparity, for a selected bending diameter, between macrobending losses at the target wavelength and macrobending losses at wavelengths longer than the target wavelength, whereby Raman scattering is frustrated at wavelengths longer than the target wavelength.Type: ApplicationFiled: May 11, 2010Publication date: November 11, 2010Applicant: OFS FITEL LLC, a Delaware Limied Liability CompanyInventors: Jeffrey W. Nicholson, Patrick W. Wisk, Man F. Yan
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Publication number: 20100284060Abstract: In a light amplification system, a fiber-based oscillator, amplifier, and cascaded Raman resonator are coupled together in series. The oscillator output is provided as an input into the amplifier, the amplifier output is provided as a pumping input into the cascaded Raman resonator, and the cascaded Raman resonator provides as an output single-mode radiation at a target wavelength. A loss element is connected between the oscillator and amplifier, whereby the oscillator is optically isolated from the amplifier and cascaded Raman resonator. A filter is coupled between the isolator and the amplifier for filtering out backward-propagating Stokes wavelengths generated in the cascaded Raman resonator. The oscillator is operable within a first power level range, and the amplifier and cascaded Raman resonator are operable within a second power level range exceeding the first power level range.Type: ApplicationFiled: May 11, 2010Publication date: November 11, 2010Applicant: OFS Fitel LLC, a Delaware Limited Liability CompanyInventor: Jeffrey W. Nicholson
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Publication number: 20100284061Abstract: In a light amplification system and technique, a pump source provides pump power at a source wavelength. The pump power is launched as an input into a cascaded Raman resonator. A wavelength-dependent loss element is connected such that it precedes the cascaded Raman resonator. The wavelength-dependent loss element is configured to transmit light power at the source wavelength with low loss, and to provide high loss at the first Stokes shift. The wavelength-dependent loss element prevents buildup of light power between the pump source and the cascaded Raman resonator, thereby preventing backward propagation of light power back into the pump source.Type: ApplicationFiled: May 11, 2010Publication date: November 11, 2010Applicant: OFS Fitel LLC, a Delaware Limited Liability CompanyInventor: Jeffrey W. Nicholson
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Patent number: 7826499Abstract: An all-fiber supercontinuum source is formed as a hybrid combination of a first section of continuum-generating fiber (such as, for example, highly-nonlinear fiber (HNLF)) spliced to a second section of continuum-extending fiber (such as, for example, photonic crystal fiber (PCF)). The second section of fiber is selected to exhibit an anomalous dispersion value in the region of the short wavelength edge of the continuum generated by the first section of fiber. A femtosecond pulse laser source may be used to supply input pulses to the section of HNLF, and the section of PCF is spliced to the termination of the section of HNLF. A section of single mode fiber (SMF) is preferably inserted between the output of the laser source and the HNLF to compress the femtosecond pulses prior to entering the HNLF.Type: GrantFiled: August 2, 2007Date of Patent: November 2, 2010Assignee: OFS Fitel LLCInventors: Jeffrey W. Nicholson, Siddharth Ramachandran
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Patent number: 7817258Abstract: 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.Type: GrantFiled: June 20, 2008Date of Patent: October 19, 2010Assignee: OFS Fitel LLCInventors: Poul Kristensen, Jeffrey W. Nicholson, Siddharth Ramachandran, Andrew D. Yablon
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Patent number: 7817684Abstract: A passively mode-locked, figure-eight laser is formed of all normal dispersion fiber, eliminating the need for using anomalous dispersion fiber. The fiber is selected to be polarization maintaining, with the remaining components of the laser (couplers, isolator, gain fiber) also formed as polarization maintaining elements. In one embodiment, a section of Yb-doped fiber is used as the gain element. An external modulation component (amplitude or phase) is preferably used to initiate the passive mode locking.Type: GrantFiled: November 14, 2007Date of Patent: October 19, 2010Assignee: OFS Fitel LLCInventor: Jeffrey W. Nicholson
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Publication number: 20100148383Abstract: A method of creating optical fiber to exhibit predetermined length-dependent characteristics (e.g., chromatic dispersion, polarization mode dispersion, cutoff wavelength, birefringence) includes the steps of: characterizing the fiber's selected characteristic(s) as a function of length; and performing a “treatment” which modifies the refractive index over the given length to adjust the defined parameter to fall within a defined tolerance window. These steps may be repeated one or more times until the measure of the parameter falls with the defined tolerance limits. The treatment process may include, for example, a low energy actinic radiation exposure, anneal, mechanical strain, DC voltage, plasma application, etc. Indeed, if the treatment process is repeated, a different technique may be used to adjust the refractive index (“different” processes include, for example, modifying the strength/time of a UV exposure, temperatures for annealing, etc.).Type: ApplicationFiled: December 15, 2008Publication date: June 17, 2010Inventors: David J. DiGiovanni, Jeffrey W. Nicholson, Paul S. Westbrook, Man F. Yan
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Publication number: 20100061407Abstract: A polarization-maintaining figure eight (PMFE) fiber laser is configured to generate ultrashort (femtosecond) output pulses by intentionally inserting asymmetry (in the form of a phase bias) into the bi-directional loop of the fiber laser. The introduction of asymmetry (via an asymmetric coupler, splice, attenuator, fiber bend, multiple amplifying sections, or the like) allows for an accumulation of phase difference within the bi-directional loop sufficient to create modelocking and generate ultrashort output pulses.Type: ApplicationFiled: September 5, 2008Publication date: March 11, 2010Inventor: Jeffrey W. Nicholson