Patents by Inventor Kazi S. Abedin
Kazi S. Abedin 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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Publication number: 20210026092Abstract: An optical system comprising an optical conduit (e.g., gain fiber or rare-earth-doped fiber) with a bend having a bend radius (R). The bend induces a tension and a compression in the fiber core, which results in a corresponding strain (?). The corresponding bend-induced strain impacts the signal properties in the core of the fiber.Type: ApplicationFiled: April 3, 2019Publication date: January 28, 2021Applicant: OFS Fitel, LLCInventors: Kazi S Abedin, David J DiGiovanni, Tristan Kremp
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Publication number: 20190140416Abstract: A fiber amplifier has a first amplification stage and a second amplification stage. The first amplification stage comprises a first gain fiber that is configured to receive, at its input end, a signal light and a pump light. The first gain fiber uses a portion of the pump light to provide first-stage amplification to the signal light. The second amplification stage comprises a second gain fiber that is configured to receive, at its input end, the first-stage-amplified signal light and residual pump light. The second gain fiber uses the residual pump light to provide second-stage amplification of the first-stage-amplified signal light and to provide, at its output end, the second-stage amplified signal light.Type: ApplicationFiled: March 28, 2018Publication date: May 9, 2019Applicant: OFS Fitel, LLCInventors: Kazi S. Abedin, David J. DiGiovanni
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Patent number: 10234344Abstract: A multi-axis force sensor is compact in that it comprises a single strand of optical fiber and a single, movable reflecting element having a reflecting surface separated from a fiber end-face by a gap, and yet is capable of measuring axially and/or laterally applied forces with high sensitivity. The force to be measured causes the reflecting surface to tilt, translate or deform. The single strand of fiber is configured to have multiple cores that carry multiple optical interrogation signals through an end-face of the fiber to incidence on the reflecting surface. The cores are configured so that the propagation vectors of the interrogation signals, as the signals emanate from the fiber end-face, make non-perpendicular angles with that end-face. Furthermore, the cores are configured to capture a portion of the interrogation signals back-reflected from the reflecting surface.Type: GrantFiled: February 3, 2017Date of Patent: March 19, 2019Assignee: OFS FITEL, LLCInventor: Kazi S Abedin
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Patent number: 9946014Abstract: An optical pedestal fiber is configured to be taperable to form a tapered fiber having a mode field diameter at the tapered end that differs from the mode field diameter at the untapered end in correspondence with the difference between the cladding diameter at the tapered end and the cladding diameter at the untapered end. A plurality of such pedestal fibers can be used to construct a tapered fiber bundle coupler that provides matching of both core pitch and mode field diameter between a plurality of input fibers and individual cores of a multicore fiber. Further, the tapered fiber bundle coupler can be constructed using a plurality of fibers, in which individual fibers are configured to have different effective refractive indices, thereby suppressing crosstalk therebetween.Type: GrantFiled: June 20, 2012Date of Patent: April 17, 2018Assignee: OFS FITEL, LLCInventors: Kazi S. Abedin, Thierry F. Taunay, Man F. Yan, Benyuan Zhu
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Publication number: 20170227410Abstract: A multi-axis force sensor is compact in that it comprises a single strand of optical fiber and a single, movable reflecting element having a reflecting surface separated from a fiber end-face by a gap, and yet is capable of measuring axially and/or laterally applied forces with high sensitivity. The force to be measured causes the reflecting surface to tilt, translate or deform. The single strand of fiber is configured to have multiple cores that carry multiple optical interrogation signals through an end-face of the fiber to incidence on the reflecting surface. The cores are configured so that the propagation vectors of the interrogation signals, as the signals emanate from the fiber end-face, make non-perpendicular angles with that end-face. Furthermore, the cores are configured to capture a portion of the interrogation signals back-reflected from the reflecting surface.Type: ApplicationFiled: February 3, 2017Publication date: August 10, 2017Applicant: OFS Fitel, LLCInventor: Kazi S. Abedin
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Patent number: 9568339Abstract: Methods and systems using one or more distributed feedback (DFB) lasers for capturing changes in the lasing environment are disclosed. Specifically, a sensor for measuring a measurand, such as pressure or temperature, or changes in a measurand, includes a fiber with at least one core, at least one fiber laser cavity formed by a single fiber grating in the core, wherein the laser operates on at least two modes along at least part of its length. The DFB laser includes a section that is bent into a non-linear shape and at least one pump laser connected to the fiber laser cavity. When the DFB laser experiences a perturbation or measurand change that changes the spacing of the modes, a change in an RF beat note is generated. This beat note can then be measured and related to the measurand change.Type: GrantFiled: December 2, 2011Date of Patent: February 14, 2017Assignee: OFS FITEL, LLCInventors: Kazi S. Abedin, Paul S. Westbrook
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Patent number: 9325152Abstract: A Raman distributed feedback (DFB) fiber laser is disclosed. It includes a pump source and a Raman gain fiber of a length smaller than 20 cm containing a distributed feedback (DFB) grating with a discrete phase structure located within no more than 10% off the center of the grating and wherein the Raman DFB fiber laser generates a laser signal with an optical spectrum, which has an optical bandwidth at half maximum optical intensity of less than 1 gigahertz (GHz) (wherein a maximum intensity frequency is different from the frequency of the pump laser). The Raman laser includes compensation for the nonlinear phase change due to Kerr effect and thermal effect resulting from absorption of the optical field, thus enhancing the conversion efficiency.Type: GrantFiled: April 25, 2012Date of Patent: April 26, 2016Assignee: OFS FITEL, LLCInventors: Kazi S. Abedin, Tristan Kremp, Jeffrey W. Nicholson, Jerome C. Porque, Paul S. Westbrook
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Patent number: 9244226Abstract: A technique is described for terminating an optical fiber with low backreflection. At a selected end of the optical fiber segment, an endface is formed at a selected angle relative to the fiber axis. A suitable material is deposited onto the angled endface to form an angled reflective surface. The angled reflective surface is configured such that light propagating along the waveguide to the selected end of the optical fiber segment is reflected back into the optical fiber segment at an angle that prevents coupling of the reflected light into the fiber core. The reflected light is dissipated along the length of the fiber segment.Type: GrantFiled: January 31, 2014Date of Patent: January 26, 2016Assignee: OFS FITEL, LLCInventors: Kazi S Abedin, David J Digiovanni, Paul S Westbrook
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Patent number: 9244218Abstract: A few-moded fiber device has several discrete sections of few-moded fibers that are separated by mode converters, with each mode converter accomplishing mode conversion between one or more pairs of modes. The mode conversions can be accomplished using a sequence, such as a periodic or cyclic sequence that would cause (1) a signal wave launched with any mode to assume every other mode for one or more times; (2) the number of times the signal remains in any modal state is substantially the same; and (3) the net signal gain or loss or group delay of the input signal is substantially the same regardless of the state of input mode. A laser few-mode amplifier is provided. An optical transmission system is also provided.Type: GrantFiled: August 10, 2012Date of Patent: January 26, 2016Assignee: OFS FITEL, LLCInventors: Kazi S. Abedin, John M. Fini, Man F. Yan
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Publication number: 20150219851Abstract: A technique is described for terminating an optical fiber with low backreflection. At a selected end of the optical fiber segment, an endface is formed at a selected angle relative to the fiber axis. A suitable material is deposited onto the angled endface to form an angled reflective surface. The angled reflective surface is configured such that light propagating along the waveguide to the selected end of the optical fiber segment is reflected back into the optical fiber segment at an angle that prevents coupling of the reflected light into the fiber core. The reflected light is dissipated along the length of the fiber segment.Type: ApplicationFiled: January 31, 2014Publication date: August 6, 2015Inventors: Kazi S Abedin, David J Digiovanni, Paul S Westbrook
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Patent number: 9083147Abstract: A Brillouin fiber laser uses a distributed feedback (DFB) fiber Bragg grating with a discrete ?-phase shift, which is offset from the physical center of the grating as a resonator. Lasing is achieved by using the SBS gain in the DFB from narrow-linewidth laser pump radiation with an optical frequency that is higher than the central pass band of the grating by an amount nominally equal to the Stokes's frequency shift, ?B. The lasing occurs at a wavelength that corresponds to the first Stokes wave. The Brillouin DFB fiber laser has a low threshold, does not require any fiber optic couplers, does not require rare-earth doping, enables connection of many DFB lasers in series, pumping using a multi-wavelength or wavelength tunable laser sources, and the laser output can be delivered along the direction of the pump propagation or in the reverse direction.Type: GrantFiled: October 29, 2012Date of Patent: July 14, 2015Assignee: OFS FITEL, LLCInventors: Paul S Westbrook, Kazi S Abedin
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Publication number: 20150192733Abstract: A few-moded fiber device has several discrete sections of few-moded fibers that are separated by mode converters, with each mode converter accomplishing mode conversion between one or more pairs of modes. The mode conversions can be accomplished using a sequence, such as a periodic or cyclic sequence that would cause (1) a signal wave launched with any mode to assume every other mode for one or more times; (2) the number of times the signal remains in any modal state is substantially the same; and (3) the net signal gain or loss or group delay of the input signal is substantially the same regardless of the state of input mode. A laser few-mode amplifier is provided. An optical transmission system is also provided.Type: ApplicationFiled: August 10, 2012Publication date: July 9, 2015Inventors: Kazi S. Abedin, John M. Fini, Man F. Yan
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Patent number: 9077148Abstract: A few-mode rare-earth-doped amplifier fiber has equalized gain for the supported signal transmission modes. The fiber has a raised-index core surrounded by a lower-index cladding region. The core has a radius a1 and an index difference ?n1 relative to the surrounding cladding region and is configured to support, at a selected signal wavelength, a set of lower-order fiber modes having an optical field with a diameter greater than 2·a1. The fiber further includes an active region, doped with a rare-earth dopant, comprising an inner portion that is coextensive with the core and an outer portion that surrounds the inner portion and extends into the cladding. The active region has an outer radius a2 greater than a1 that encompasses the optical field of the set of lower-order fiber modes at the selected signal wavelength.Type: GrantFiled: September 15, 2014Date of Patent: July 7, 2015Assignee: OFS FITEL, LLCInventors: Kazi S. Abedin, Man F. Yan
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Publication number: 20150077837Abstract: A few-mode rare-earth-doped amplifier fiber has equalized gain for the supported signal transmission modes. The fiber has a raised-index core surrounded by a lower-index cladding region. The core has a radius a1 and an index difference ?n1 relative to the surrounding cladding region and is configured to support, at a selected signal wavelength, a set of lower-order fiber modes having an optical field with a diameter greater than 2·a1. The fiber further includes an active region, doped with a rare-earth dopant, comprising an inner portion that is coextensive with the core and an outer portion that surrounds the inner portion and extends into the cladding. The active region has an outer radius a2 greater than a1 that encompasses the optical field of the set of lower-order fiber modes at the selected signal wavelength.Type: ApplicationFiled: September 15, 2014Publication date: March 19, 2015Applicant: OFS FITEL, LLCInventors: Kazi S. Abedin, Man F. Yan
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Publication number: 20140269789Abstract: A Brillouin fiber laser uses a distributed feedback (DFB) fiber Bragg grating with a discrete ?-phase shift, which is offset from the physical center of the grating as a resonator. Lasing is achieved by using the SBS gain in the DFB from narrow-linewidth laser pump radiation with an optical frequency that is higher than the central pass band of the grating by an amount nominally equal to the Stokes's frequency shift, ?B. The lasing occurs at a wavelength that corresponds to the first Stokes wave. The Brillouin DFB fiber laser has a low threshold, does not require any fiber optic couplers, does not require rare-earth doping, enables connection of many DFB lasers in series, pumping using a multi-wavelength or wavelength tunable laser sources, and the laser output can be delivered along the direction of the pump propagation or in the reverse direction.Type: ApplicationFiled: October 29, 2012Publication date: September 18, 2014Inventors: Paul S. Westbrook, Kazi S. Abedin
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Publication number: 20140119694Abstract: An optical pedestal fiber is configured to be taperable to form a tapered fiber having a mode field diameter at the tapered end that differs from the mode field diameter at the untapered end in correspondence with the difference between the cladding diameter at the tapered end and the cladding diameter at the untapered end. A plurality of such pedestal fibers can be used to construct a tapered fiber bundle coupler that provides matching of both core pitch and mode field diameter between a plurality of input fibers and individual cores of a multicore fiber. Further, the tapered fiber bundle coupler can be constructed using a plurality of fibers, in which individual fibers are configured to have different effective refractive indices, thereby suppressing crosstalk therebetween.Type: ApplicationFiled: June 20, 2012Publication date: May 1, 2014Applicant: OFS Fitel, LLCInventors: Kazi S Abedin, Thierry F. Taunay, Man F. Yan, Benyuan Zhu
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Publication number: 20140112357Abstract: A Raman distributed feedback (DFB) fiber laser is disclosed. It includes a pump source and a Raman gain fiber of a length smaller than 20 cm containing a distributed feedback (DFB) grating with a discrete phase structure located within no more than 10% off the center of the grating and wherein the Raman DFB fiber laser generates a laser signal with an optical spectrum, which has an optical bandwidth at half maximum optical intensity of less than 1 gigahertz (GHz) (wherein a maximum intensity frequency is different from the frequency of the pump laser). The Raman laser includes compensation for the nonlinear phase change due to Kerr effect and thermal effect resulting from absorption of the optical field, thus enhancing the conversion efficiency.Type: ApplicationFiled: April 25, 2012Publication date: April 24, 2014Inventors: Kazi S. Abedin, Tristan Kremp, Jeffrey W. Nicholson, Jerom C. Porque, Paul S. Westbrook
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Publication number: 20140054451Abstract: Methods and systems using one or more distributed feedback (DFB) lasers for capturing changes in the lasing environment are disclosed. Specifically, a sensor for measuring a measurand, such as pressure or temperature, or changes in a measurand, includes a fiber with at least one core, at least one fiber laser cavity formed by a single fiber grating in the core, wherein the laser operates on at least two modes along at least part of its length. The DFB laser includes a section that is bent into a non-linear shape and at least one pump laser connected to the fiber laser cavity. When the DFB laser experiences a perturbation or measurand change that changes the spacing of the modes, a change in an RF beat note is generated. This beat note can then be measured and related to the measurand change.Type: ApplicationFiled: December 2, 2011Publication date: February 27, 2014Applicant: OFS FITEL, LLCInventors: Kazi S. Abedin, Paul S. Westbrook