Patents by Inventor Kannan Raj

Kannan Raj 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).

  • Patent number: 10170888
    Abstract: The disclosed embodiments provide a laser source comprising a silicon waveguide formed in a silicon layer, and a cascaded array of hybrid distributed feedback (DFB) lasers formed by locating sections of III-V gain material over the silicon waveguide. Each DFB laser in the cascaded array comprises a section of III-V gain material located over the silicon waveguide, wherein the section of III-V gain material includes an active region that generates light, and a Bragg grating located between the III-V gain material and the silicon waveguide. This Bragg grating has a resonance frequency within a gain bandwidth of the section of III-V material and is transparent to frequencies that differ from the resonance frequency. Moreover, each DFB laser has a hybrid mode that resides partially in the III-V gain material and partially in silicon.
    Type: Grant
    Filed: November 3, 2016
    Date of Patent: January 1, 2019
    Assignee: Oracle International Corporation
    Inventors: Xuezhe Zheng, Ying Luo, Ashok V. Krishnamoorthy, Kannan Raj
  • Publication number: 20180231807
    Abstract: The disclosed embodiments provide a laser source comprising a silicon waveguide formed in a silicon layer, and a cascaded array of hybrid distributed feedback (DFB) lasers formed by locating sections of III-V gain material over the silicon waveguide. Each DFB laser in the cascaded array comprises a section of III-V gain material located over the silicon waveguide, wherein the section of III-V gain material includes an active region that generates light, and a Bragg grating located between the III-V gain material and the silicon waveguide. This Bragg grating has a resonance frequency within a gain bandwidth of the section of III-V material and is transparent to frequencies that differ from the resonance frequency. Moreover, each DFB laser has a hybrid mode that resides partially in the III-V gain material and partially in silicon.
    Type: Application
    Filed: November 3, 2016
    Publication date: August 16, 2018
    Applicant: Oracle International Corporation
    Inventors: Xuezhe Zheng, Ying Luo, Ashok V. Krishnamoorthy, Kannan Raj
  • Patent number: 9935424
    Abstract: An integrated circuit includes an optical source (such as a laser) with a lens, which is disposed on an isolator. This isolator is disposed on a semiconductor layer in a silicon-on-insulator (SOI) platform that includes an optical coupler and an optical waveguide. During operation, the optical source generates an optical signal that propagates toward the isolator so that the lens focuses the optical signal. Furthermore, the isolator reduces or eliminates back reflection of the optical signal toward the optical source, and the optical coupler couples the optical signal into the optical waveguide.
    Type: Grant
    Filed: August 7, 2015
    Date of Patent: April 3, 2018
    Assignee: ORACLE INTERNATIONAL CORPORATION
    Inventors: Xuezhe Zheng, Ashok V. Krishnamoorthy, Kannan Raj
  • Patent number: 9819421
    Abstract: An optical receiver includes: an active transimpedance amplifier (TIA) that converts a photocurrent from a photosensor into an active voltage signal; a high-speed amplifier that amplifies the active voltage signal to produce an amplified voltage signal that comprises an output for the optical receiver; and a reference-voltage-generation circuit that generates a reference voltage for the high-speed amplifier. This reference-voltage-generation circuit includes a dummy TIA that is identical to the active TIA, but does not receive a live input signal, and produces a dummy voltage signal. It also includes a low-speed amplifier which includes: an active input that receives the active voltage signal from the active TIA output; a dummy input that receives the dummy voltage signal from the dummy TIA output; and an output that controls directly or indirectly the reference voltage for the high-speed amplifier.
    Type: Grant
    Filed: July 7, 2016
    Date of Patent: November 14, 2017
    Assignee: Oracle International Corporation
    Inventors: Jingqiong Xie, Ashok V. Krishnamoorthy, Xuezhe Zheng, Jeffrey W. Denq, Kannan Raj, John E. Cunningham, Hiren D. Thacker
  • Patent number: 9735989
    Abstract: The disclosed embodiments relate to the design of an equalizer that uses both cross-coupled cascodes and inductive peaking to reduce distortion in a signal received from a communication channel by attenuating lower frequencies and amplifying higher frequencies. At lower frequencies, when the effects of inductive impedance within the equalizer are negligible, the equalizer essentially functions as a traditional cascode amplifier that presents high gain. At higher frequencies, the increases in inductive impedances within the equalizer act to boost a gain of the equalizer.
    Type: Grant
    Filed: June 23, 2016
    Date of Patent: August 15, 2017
    Assignee: ORACLE INTERNATIONAL CORPORATION
    Inventors: Jingqiong Xie, Ashok V. Krishnamoorthy, Xuezhe Zheng, Jeffrey W. Denq, Kannan Raj
  • Patent number: 9671572
    Abstract: A chip package includes an integrated circuit and an optical integrated circuit (such as a hybrid integrated circuit) with an optical source and/or an optical receiver. The integrated circuit and the optical integrated circuit may be proximate to each other on opposite sides of an interposer in the chip package. Moreover, the integrated circuit may include a driver circuit of electrical signals for the optical source and/or a receiver circuit of electrical signals from the optical receiver. Furthermore, the optical integrated circuit may be positioned in a hole or an etch pit in a substrate, and an alignment feature may mechanically couple the substrate to an optical-fiber assembly, so that the optical-fiber assembly is positioned relative to the interposer and the optical integrated circuit. In particular, the optical-fiber assembly may partially overlap the interposer, so that optical signals are provided and/or received from the optical integrated circuit through the interposer.
    Type: Grant
    Filed: September 22, 2014
    Date of Patent: June 6, 2017
    Assignee: ORACLE INTERNATIONAL CORPORATION
    Inventors: Patrick J. Decker, Kannan Raj, Alan T. Hilton-Nickel
  • Patent number: 9519105
    Abstract: A multi-chip module (MCM) is described. This MCM includes two substrates that are passively self-assembled on another substrate using hydrophilic and hydrophobic materials on facing surfaces of the substrates and liquid surface tension as the restoring force. In particular, regions with a hydrophilic material on the two substrates overlap regions with the hydrophilic material on the other substrate. These regions on the other substrate may be surrounded by a region with a hydrophobic material. In addition, spacers on a surface of at least one of the two substrates may align optical waveguides disposed on the two substrates, so that the optical waveguides are coplanar. This fabrication technique may allow low-loss hybrid optical sources to be fabricated by edge coupling the two substrates. For example, a first of the two substrates may be a III/V compound semiconductor and a second of the two substrates may be a silicon-on-insulator photonic chip.
    Type: Grant
    Filed: June 21, 2016
    Date of Patent: December 13, 2016
    Assignee: ORACLE INTERNATIONAL CORPORATION
    Inventors: Ivan Shubin, Xuezhe Zheng, Jin Hyoung Lee, Kannan Raj, Ashok V. Krishnamoorthy
  • Patent number: 9470855
    Abstract: A multi-chip module (MCM) is described. This MCM includes two substrates that are passively self-assembled on another substrate using hydrophilic and hydrophobic materials on facing surfaces of the substrates and liquid surface tension as the restoring force. In particular, regions with a hydrophilic material on the two substrates overlap regions with the hydrophilic material on the other substrate. These regions on the other substrate may be surrounded by a region with a hydrophobic material. In addition, spacers on a surface of at least one of the two substrates may align optical waveguides disposed on the two substrates, so that the optical waveguides are coplanar. This fabrication technique may allow low-loss hybrid optical sources to be fabricated by edge coupling the two substrates. For example, a first of the two substrates may be a III/V compound semiconductor and a second of the two substrates may be a silicon-on-insulator photonic chip.
    Type: Grant
    Filed: August 11, 2015
    Date of Patent: October 18, 2016
    Assignee: ORACLE INTERNATIONAL CORPORATION
    Inventors: Ivan Shubin, Xuezhe Zheng, Jin-Hyoung Lee, Kannan Raj, Ashok V. Krishnamoorthy
  • Publication number: 20160294155
    Abstract: An integrated circuit includes an optical source (such as a laser) with a lens, which is disposed on an isolator. This isolator is disposed on a semiconductor layer in a silicon-on-insulator (SOI) platform that includes an optical coupler and an optical waveguide. During operation, the optical source generates an optical signal that propagates toward the isolator so that the lens focuses the optical signal. Furthermore, the isolator reduces or eliminates back reflection of the optical signal toward the optical source, and the optical coupler couples the optical signal into the optical waveguide.
    Type: Application
    Filed: August 7, 2015
    Publication date: October 6, 2016
    Applicant: ORACLE INTERNATIONAL CORPORATION
    Inventors: Xuezhe Zheng, Ashok V. Krishnamoorthy, Kannan Raj
  • Publication number: 20160085038
    Abstract: A chip package includes an integrated circuit and an optical integrated circuit (such as a hybrid integrated circuit) with an optical source and/or an optical receiver. The integrated circuit and the optical integrated circuit may be proximate to each other on opposite sides of an interposer in the chip package. Moreover, the integrated circuit may include a driver circuit of electrical signals for the optical source and/or a receiver circuit of electrical signals from the optical receiver. Furthermore, the optical integrated circuit may be positioned in a hole or an etch pit in a substrate, and an alignment feature may mechanically couple the substrate to an optical-fiber assembly, so that the optical-fiber assembly is positioned relative to the interposer and the optical integrated circuit. In particular, the optical-fiber assembly may partially overlap the interposer, so that optical signals are provided and/or received from the optical integrated circuit through the interposer.
    Type: Application
    Filed: September 22, 2014
    Publication date: March 24, 2016
    Inventors: Patrick J. Decker, Kannan Raj, Alan T. Hilton-Nickel
  • Patent number: 9257814
    Abstract: A hybrid optical source that provides an optical signal having a wavelength is described. This hybrid optical source comprises an optical amplifier (such as a III-V semiconductor optical amplifier) that is butt-coupled or vertically coupled to a silicon-on-insulator (SOI) platform, and which outputs an optical signal. The SOI platform comprises an optical waveguide that conveys the optical signal. A temperature-compensation element included in the optical waveguide compensates for temperature dependence of the indexes of refraction of the optical amplifier and the optical waveguide. In addition, a reflector, included in or in-line with the optical waveguide and after the temperature-compensation element, reflects a portion of the optical signal and transmits another portion of the optical signal that has the wavelength.
    Type: Grant
    Filed: December 11, 2014
    Date of Patent: February 9, 2016
    Assignee: ORACLE INTERNATIONAL CORPORATION
    Inventors: Stevan S. Djordjevic, Xuezhe Zheng, Jin Yao, John E. Cunningham, Kannan Raj, Ashok V. Krishnamoorthy
  • Patent number: 9232149
    Abstract: An embodiment of the invention is a method of generating a final exposure setting, including, (a) selecting one of a number of predetermined exposure settings as a current exposure setting for a solid state camera having a camera imager, (b) generating a captured scene by the camera imager using the current exposure setting, (c) selecting according to an automated search methodology another one of the exposure settings to be the current setting in response to the captured scene being underexposed or overexposed, and, (d) repeating (b) and (c) until the captured scene is neither underexposed or overexposed.
    Type: Grant
    Filed: February 17, 2014
    Date of Patent: January 5, 2016
    Assignee: INTEL CORPORATION
    Inventors: Edward P. Tomaszewski, Kannan Raj, Amy E. Hansen, Cynthia Bell
  • Patent number: 9091806
    Abstract: An integrated circuit includes a holographic recording material substantially filling a cavity in a semiconductor layer. During operation of the integrated circuit, a holographic pattern in the holographic recording is reconstructed and used to diffract an optical signal propagating in a plane of an optical waveguide, which is defined in the semiconductor layer out of the plane through the cavity. In this way, the holographic recording material may be used to couple the optical signal to an optical fiber or another integrated circuit.
    Type: Grant
    Filed: April 5, 2012
    Date of Patent: July 28, 2015
    Assignee: ORACLE INTERNATIONAL CORPORATION
    Inventors: Xuezhe Zheng, Ashok V. Krishnamoorthy, Kannan Raj, James R. Adleman
  • Patent number: 9052464
    Abstract: An optical device has a waveguide immobilized on a base. A lens is defined by the base. A reflecting side reflects a light signal that travels on an optical pathway that extends through the lens and into the waveguide. The reflecting side is positioned to reflect the light signal as the light signal travels along a portion of the optical pathway between the lens and the waveguide. An optical insulator that confines the light signal within the waveguide. The portion of the optical pathway between the lens and the waveguide extends through the optical insulator such that the light signal is transmitted through the optical insulator.
    Type: Grant
    Filed: May 6, 2013
    Date of Patent: June 9, 2015
    Assignees: Kotura, Inc., Oracle International Corporation
    Inventors: Shirong Liao, Mehdi Asghari, Dazeng Feng, Roshanak Shafiiha, Daniel C. Lee, Wei Qian, Xuezhe Zheng, Ashok Krishnamoorthy, John E. Cunningham, Kannan Raj
  • Patent number: 8982563
    Abstract: A chip package includes a processor, an interposer chip and a voltage regulator module (VRM). The interposer chip is electrically coupled to the processor by first electrical connectors proximate to a surface of the interposer chip. Moreover, the interposer chip includes second electrical connectors proximate to another surface of the interposer chip, which are electrically coupled to the first electrical connectors by through-substrate vias (TSVs) in the interposer chip. Note that the second electrical connectors can electrically couple the interposer chip to a circuit board. Furthermore, the VRM is electrically coupled to the processor by the interposer chip, and is proximate to the processor in the chip package, thereby reducing voltage droop. For example, the VRM may be electrically coupled to the surface of the interposer chip, and may be adjacent to the processor. Alternatively, the VRM may be electrically coupled to the other surface of the interposer chip.
    Type: Grant
    Filed: June 28, 2011
    Date of Patent: March 17, 2015
    Assignee: Oracle International Corporation
    Inventors: Kannan Raj, Ivan Shubin, John E. Cunningham
  • Patent number: 8873961
    Abstract: An optical de-multiplexer (de-MUX) that includes an optical device that images and diffracts an optical signal using a reflective geometry is described, where a free spectral range (FSR) of the optical device associated with a given diffraction order abuts FSRs associated with adjacent diffraction orders. Moreover, the channel spacings within diffraction orders and between adjacent diffraction orders are equal to the predefined channel spacing associated with the optical signal. As a consequence, the optical device has a comb-filter output spectrum, which reduces a tuning energy of the optical device by eliminating spectral gaps between diffraction orders of the optical device.
    Type: Grant
    Filed: August 9, 2011
    Date of Patent: October 28, 2014
    Assignee: Oracle International Corporation
    Inventors: Ying Luo, Xuezhe Zheng, Guoliang Li, Kannan Raj, Ashok V. Krishnamoorthy
  • Patent number: 8767091
    Abstract: An embodiment of the invention is a method of generating a final exposure setting, including, (a) selecting one of a number of predetermined exposure settings as a current exposure setting for a solid state camera having a camera imager, (b) generating a captured scene by the camera imager using the current exposure setting, (c) selecting according to an automated search methodology another one of the exposure settings to be the current setting in response to the captured scene being underexposed or overexposed, and, (d) repeating (b) and (c) until the captured scene is neither underexposed or overexposed.
    Type: Grant
    Filed: September 27, 2011
    Date of Patent: July 1, 2014
    Assignee: Intel Corporation
    Inventors: Cynthia S. Bell, Edward P. Tomaszewski, Amy E. Hansen, Kannan Raj
  • Publication number: 20140160313
    Abstract: An embodiment of the invention is a method of generating a final exposure setting, including, (a) selecting one of a number of predetermined exposure settings as a current exposure setting for a solid state camera having a camera imager, (b) generating a captured scene by the camera imager using the current exposure setting, (c) selecting according to an automated search methodology another one of the exposure settings to be the current setting in response to the captured scene being underexposed or overexposed, and, (d) repeating (b) and (c) until the captured scene is neither underexposed or overexposed.
    Type: Application
    Filed: February 17, 2014
    Publication date: June 12, 2014
    Inventors: Edward P. Tomaszewski, Kannan Raj, Amy E. Hansen, Cynthia Bell
  • Publication number: 20130265624
    Abstract: An integrated circuit includes a holographic recording material substantially filling a cavity in a semiconductor layer. During operation of the integrated circuit, a holographic pattern in the holographic recording is reconstructed and used to diffract an optical signal propagating in a plane of an optical waveguide, which is defined in the semiconductor layer out of the plane through the cavity. In this way, the holographic recording material may be used to couple the optical signal to an optical fiber or another integrated circuit.
    Type: Application
    Filed: April 5, 2012
    Publication date: October 10, 2013
    Applicant: ORACLE INTERNATIONAL CORPORATION
    Inventors: Xuezhe Zheng, Ashok V. Krishnamoorthy, Kannan Raj, James R. Adleman
  • Patent number: 8548287
    Abstract: In an MCM, an optical signal is conveyed by an optical waveguide disposed on a surface of a first substrate to an optical coupler having a vertical facet. This optical coupler has an optical mode that is different than the optical mode of the optical waveguide. For example, the spatial extent of the optical mode associated with the optical coupler may be larger, thereby reducing optical losses and sensitivity to alignment errors. Then, the optical signal is directly coupled from the vertical facet to a facing vertical facet of an identical optical coupler on another substrate, and the optical signal is conveyed in another optical waveguide disposed on the other substrate.
    Type: Grant
    Filed: November 10, 2011
    Date of Patent: October 1, 2013
    Assignee: Oracle International Corporation
    Inventors: Hiren D. Thacker, Xuezhe Zheng, Ivan Shubin, Kannan Raj, John E. Cunningham, Ashok V. Krishnamoorthy