Patents by Inventor Mohammed N. Islam
Mohammed N. Islam 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: 6972886Abstract: In one aspect of the invention, an apparatus operable to provide optical signal processing includes an inner conductive layer including an at least substantially conductive material and a plurality of at least partially reflective mirror strips disposed outwardly from the inner conductive layer and operable to receive an input optical signal, wherein none of the plurality of strips has a width greater than 40 microns. At least some of the strips are operable to undergo a partial rotation in response to a control signal, the partial rotation resulting in a diffraction of the input optical signal wherein a majority of the diffracted input signal is communicated in one direction.Type: GrantFiled: November 19, 2004Date of Patent: December 6, 2005Assignee: Cheetah Omni, LLCInventors: Mohammed N. Islam, Amos Kuditcher
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Patent number: 6954303Abstract: A multi-stage optical amplifier that has an optical fiber with a first length of amplifier fiber and a second length of amplifier fiber. The optical fiber is configured to be coupled to a signal source that produces at least a signal wavelength ?s and a pump source that produces a pump wavelength ?p. Pump wavelength ?p is less than signal wavelength ?s. Signal input, signal output and pump input ports are each coupled to the optical fiber. A first lossy member is coupled to the optical fiber and positioned between the first and second lengths of amplifier fiber. A pump shunt is coupled to the signal input port and the signal output port.Type: GrantFiled: November 6, 2001Date of Patent: October 11, 2005Assignee: Xtera Communications, Inc.Inventor: Mohammed N. Islam
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Patent number: 6950225Abstract: An optical switch element is described, which includes a fixed layer disposed outwardly from a substrate and a movable mirror assembly disposed outwardly from the fixed layer. The moveable mirror assembly is operable to move relative to the fixed layer responsive to a voltage applied to the movable mirror assembly. In a particular embodiment, the movable mirror assembly includes an inner strip spaced apart from the fixed layer by a first distance and an outer strip disposed approximately adjacent to the inner strip and spaced apart from the fixed layer by a second distance which is greater than the first distance. The optical transmission of the optical switch element changes depending on the position of the movable mirror assembly.Type: GrantFiled: November 19, 2004Date of Patent: September 27, 2005Assignee: Cheetah Omni, LLCInventors: Mohammed N. Islam, Amos Kuditcher
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Patent number: 6943925Abstract: A switching element capable of being used in an optical processing device includes an optical signal separator operable to separate a multiple wavelength optical signal into one or more optical signal wavelengths. The switching element further includes a plurality of semiconductor optical amplifiers located on a single semiconductor substrate. The plurality of semiconductor optical amplifiers operable to perform an optical switching operation on at least one of the optical signal wavelengths. The switching element also includes a controller operable to generate a control signal that affects the optical switching operation performed by one or more of the plurality of semiconductor optical amplifiers.Type: GrantFiled: November 25, 2003Date of Patent: September 13, 2005Assignee: Cheetah Omni, LLCInventor: Mohammed N. Islam
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Patent number: 6943936Abstract: A Raman amplifier includes a Raman gain fiber comprising a length of high-dispersion gain fiber and operable to receive at least one optical signal. The Raman amplifier also includes at least one pump source capable of generating at least one pump signal that co-propagates within the Raman gain fiber with at least a portion of the at least one optical signal received by the Raman gain fiber. The length of the high-dispersion gain fiber is at least ten (10) times a walk off length between the at least one pump signal and at least one wavelength of the at least one optical signal received by the Raman gain fiber. In addition, the length of high-dispersion gain fiber is at least two (2) times a walk off length between at least two optical signal wavelengths of the at least one optical signal received by the Raman gain fiber.Type: GrantFiled: August 2, 2002Date of Patent: September 13, 2005Assignees: The Regents of the University of Michigan, Xtera Communications, Inc.Inventors: Mohammed N. Islam, Michael J. Freeman
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Patent number: 6940647Abstract: In one aspect of the invention, a polarization controller includes a first polarization beam splitter operable to receive an input optical signal having an input state of polarization and to separate the signal into a first and a second principal mode of polarization. The polarization controller further includes at least three stages of phase shifters each operable to introduce a phase shift between the first and second principal modes, at least one phase shifter comprising a beam splitter that is shared with at least one other of the phase shifters. The at least three stages of phase shifters include a first stage coupled to the first polarization beam splitter and a last stage coupled to a second polarization beam splitter. The second polarization beam splitter is operable to receive phase shifted copies of the first and second principal modes, and to align the phase shifted copies of the principal modes to an output state of polarization.Type: GrantFiled: October 28, 2004Date of Patent: September 6, 2005Assignee: Cheetah Omni, LLCInventors: Mohammed N. Islam, Amos Kuditcher
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Patent number: 6924926Abstract: A laser diode pump includes a plurality of laser diodes each capable of generating a lasing wavelength. The laser diode pump further includes at least one wavelength combiner operable to combine the plurality of lasing wavelengths generated by the plurality of laser diodes into a multiple wavelength pump signal. In one particular embodiment, at least two of the plurality of lasing wavelengths generated by the plurality of laser diodes comprise a wavelength between 1270 nm and 1350 nm.Type: GrantFiled: August 2, 2002Date of Patent: August 2, 2005Assignees: Xtera Communications, Inc., The Regents of the University of MichiganInventors: Mohammed N. Islam, Michael J. Freeman
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Patent number: 6919986Abstract: A broadband fiber transmission system includes a transmission line with at least one zero dispersion wavelength ?o and transmits an optical signal of ?. The transmission line includes a distributed Raman amplifier that amplifies the optical signal through Raman gain. One or more pump sources are included and operated at wavelengths ?p for generating a pump light to pump the Raman amplifier. ? is close to ?0 and ?0 is less than 1540 nm or greater than 1560 nm.Type: GrantFiled: July 25, 2003Date of Patent: July 19, 2005Assignee: Xtera Communications, Inc.Inventor: Mohammed N. Islam
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Patent number: 6914717Abstract: A nonlinear polarization amplifier stage includes a gain medium operable to receive a multiple wavelength optical signal. The amplifier further includes a pump assembly operable to generate a plurality of pump wavelengths forming a pump spectrum comprising a plurality of peaks. The amplifier also includes a coupler operable to introduce the at least one of the plurality of pump wavelengths to the gain medium to facilitate amplification of at least a portion of the multiple wavelength optical signal through nonlinear polarization. In one particular example, at least a wavelength or an intensity of the at least one of the plurality of pump wavelengths is manipulated to affect the shape of a gain curve associated with the multiple wavelength optical signal in the amplifier stage.Type: GrantFiled: July 1, 2002Date of Patent: July 5, 2005Assignee: Xtera Communications, Inc.Inventor: Mohammed N. Islam
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Patent number: 6900919Abstract: In one aspect of the invention, an apparatus operable to provide optical signal processing includes an inner conductive layer including an at least substantially conductive material and a plurality of at least partially reflective mirror strips disposed outwardly from the inner conductive layer and operable to receive an input optical signal, wherein none of the plurality of strips has a width greater than 40 microns. At least some of the strips are operable to undergo a partial rotation in response to a control signal, the partial rotation resulting in a diffraction of the input optical signal wherein a majority of the diffracted input signal is communicated in one direction.Type: GrantFiled: January 21, 2003Date of Patent: May 31, 2005Assignee: Cheetah Omni, LLCInventors: Mohammed N. Islam, Amos Kuditcher
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Patent number: 6888661Abstract: A tunable optical device includes a thin film device. The thin film device includes a plurality of cavities each including an electro-optic material. The electro-optic material includes an optical characteristic capable of being manipulated by application of an electric field. In this embodiment, at least some of the plurality of cavities are coherently coupled to others of the plurality of cavities. In this embodiment, the plurality of cavities include a sufficient number of cavities to result in an approximately square frequency response for the device.Type: GrantFiled: June 13, 2002Date of Patent: May 3, 2005Assignee: Cheetah Omni, LLCInventors: Mohammed N. Islam, Amos Kuditcher
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Patent number: 6885498Abstract: A multi-stage optical amplifier includes at least a distributed Raman amplifier fiber and a discrete amplifier fiber. The amplifier is configured to be coupled to at least one signal source that produces a plurality of signal wavelengths ?s; and at least a first pump source that produces one or more pump beam wavelengths ?p. A signal input port is coupled to the amplifier. A signal output port is coupled to the amplifier. The distributed Raman and discrete amplifier fibers are positioned between the signal input port and the signal output port. A first pump input port is coupled to a first end of the distributed Raman amplifier fiber. A second pump input port is coupled to a second end of the distributed Raman amplifier fiber. The first end is located closer to the signal input port than the second end. A third pump input port is coupled to the discrete amplifier fiber.Type: GrantFiled: December 10, 2001Date of Patent: April 26, 2005Assignee: Xtera Communications, Inc.Inventor: Mohammed N. Islam
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Patent number: 6882771Abstract: In one aspect of the invention, a gain equalizer comprises a wavelength division demultiplexer operable to separate one or more communication bands into a plurality of wavelengths and an array of phase shifter stages. Each phase shifter stage comprises a micro-electro-optic system (MEMS) device comprising a moveable mirror layer operable to receive a first copy of an input signal from a beam splitter and to reflect the first copy of the input signal for combination with a second copy of the input signal at an output to form an output signal. The moveable mirror layer is displaceable in a substantially piston-like motion to introduce a phase shift between the first and second signal copies at the output, the amplitude of the output signal varying depending on the displacement of the moveable mirror layer.Type: GrantFiled: December 9, 2003Date of Patent: April 19, 2005Assignee: Cheetah Omni, LLCInventors: Mohammed N. Islam, Amos Kuditcher
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Patent number: 6876489Abstract: A Raman amplifier apparatus includes an optical transmission line with an input to receive an optical signal, an output that passes the optical signal, a first Raman gain fiber and a second Raman gain fiber. A first WDM is positioned between the second Raman gain fiber and the output. A first set of pump wavelengths is input to the first WDM. A second WDM is positioned between the first and second Raman gain fibers. A second set of pump wavelengths is input to the second WDM. At least a portion of the first set of pump wavelengths are different than the second set of pump wavelengths. The first and second set of pump wavelengths propagate in the same direction.Type: GrantFiled: April 15, 2003Date of Patent: April 5, 2005Assignee: Xtera Communications, Inc.Inventors: Mohammed N. Islam, Carl Dewilde, Michael Freeman
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Patent number: 6859301Abstract: An optical switch element is described, which includes a fixed layer disposed outwardly from a substrate and a movable mirror assembly disposed outwardly from the fixed layer. The moveable mirror assembly is operable to move relative to the fixed layer responsive to a voltage applied to the movable mirror assembly. In a particular embodiment, the movable mirror assembly includes an inner strip spaced apart from the fixed layer by a first distance and an outer strip disposed approximately adjacent to the inner strip and spaced apart from the fixed layer by a second distance which is greater than the first distance. The optical transmission of the optical switch element changes depending on the position of the movable mirror assembly.Type: GrantFiled: May 19, 2004Date of Patent: February 22, 2005Assignee: Cheetah Omni, LLCInventors: Mohammed N. Islam, Amos Kuditcher
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Patent number: 6856459Abstract: In one aspect of the invention, a polarization controller includes a first polarization beam splitter operable to receive an input optical signal having an input state of polarization and to separate the signal into a first and a second principal mode of polarization. The polarization controller further includes at least three stages of phase shifters each operable to introduce a phase shift between the first and second principal modes, at least one phase shifter comprising a beam splitter that is shared with at least one other of the phase shifters. The at least three stages of phase shifters include a first stage coupled to the first polarization beam splitter and a last stage coupled to a second polarization beam splitter. The second polarization beam splitter is operable to receive phase shifted copies of the first and second principal modes, and to align the phase shifted copies of the principal modes to an output state of polarization.Type: GrantFiled: December 22, 2000Date of Patent: February 15, 2005Assignee: Cheetah Omni, LLCInventors: Mohammed N. Islam, Amos Kuditcher
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Patent number: 6847479Abstract: In one aspect of the invention, an apparatus operable to provide optical signal processing includes an inner conductive layer including an at least substantially conductive material and a plurality of at least partially reflective mirror strips disposed outwardly from the inner conductive layer and operable to receive an input optical signal, wherein none of the plurality of strips has a width greater than 40 microns. At least some of the strips are operable to undergo a partial rotation in response to a control signal, the partial rotation resulting in a diffraction of the input optical signal wherein a majority of the diffracted input signal is communicated in one direction.Type: GrantFiled: August 27, 2003Date of Patent: January 25, 2005Assignee: Cheetah Omni, LLCInventors: Mohammed N. Islam, Amos Kuditcher
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Patent number: 6844974Abstract: In one aspect of the invention, an apparatus operable to provide optical signal processing includes an inner conductive layer including an at least substantially conductive material and a plurality of at least partially reflective mirror strips disposed outwardly from the inner conductive layer and operable to receive an input optical signal, wherein none of the plurality of strips has a width greater than 40 microns. At least some of the strips are operable to undergo a partial rotation in response to a control signal, the partial rotation resulting in a diffraction of the input optical signal wherein a majority of the diffracted input signal is communicated in one direction.Type: GrantFiled: July 9, 2002Date of Patent: January 18, 2005Assignee: Cheetah Omni, LLCInventors: Mohammed N. Islam, Amos Kuditcher
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Patent number: 6833946Abstract: This invention describes new developments in Sagnac Raman amplifiers and cascade lasers to improve their performance. The Raman amplifier bandwidth is broadened by using a broadband pump or by combining a cladding-pumped fiber laser with the Sagnac Raman cavity. The broader bandwidth is also obtained by eliminating the need for polarization controllers in the Sagnac cavity by using an all polarization maintaining configuration, or at least using loop mirrors that maintain polarization. The polarization maintaining cavities have the added benefit of being environmentally stable and appropriate for turn-key operation. The noise arising from sources such as double Rayleigh scattering is reduced by using the Sagnac cavity in combination with a polarization diversity pumping scheme, where the pump is split along two axes of the fiber. This also leads to gain for the signal that is independent of the signal polarization.Type: GrantFiled: September 23, 2002Date of Patent: December 21, 2004Assignee: Xtera Communications, Inc.Inventor: Mohammed N. Islam
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Patent number: 6819478Abstract: A fiber optic transmission system with low cost transmitter compensation includes an electro-absorption modulated laser operable to generate an optical signal for transmission over a fiber optic communication link. The system further includes a Raman amplifier stage coupled to the communication link, the Raman amplifier stage having a gain medium including a dispersion compensating fiber. The dispersion compensating fiber is operable to at least partially compensate for a distortion caused by the electro-absorption modulated laser. The Raman amplifier stage is operable to at least partially compensate for a loss associated with the dispersion compensation fiber.Type: GrantFiled: March 15, 2002Date of Patent: November 16, 2004Assignee: Xtera Communications, Inc.Inventor: Mohammed N. Islam