Patents by Inventor Ashok V. Krishnamoorthy

Ashok V. Krishnamoorthy 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: 10826272
    Abstract: An optical source may include an optical gain chip that provides an optical signal and that is optically coupled to an SOI chip. The optical gain chip may include a reflective layer. Moreover, the SOI chip may include: a first optical waveguide, a first ring resonator that selectively optically coupled to a second optical waveguide and that performs phase modulation and filtering of the optical signal, the second optical waveguide, an amplitude modulator, and an output port. Note that the reflective layer in the optical gain chip and the amplitude modulator may define an optical cavity. Furthermore, a resonance of the first ring resonator may be aligned with a lasing wavelength, and the resonance of the first ring resonator and a resonance of the amplitude modulator may be offset from each other. Additionally, modulation of the first ring resonator and the amplitude modulator may be in-phase with each other.
    Type: Grant
    Filed: July 18, 2018
    Date of Patent: November 3, 2020
    Assignee: Axalume, Inc.
    Inventors: Jock Bovington, Xuezhe Zheng, Saman Saeedi, Ashok V. Krishnamoorthy
  • Patent number: 10714895
    Abstract: An optical source may include an optical gain chip that provides an optical signal and that is optically coupled to an SOI chip. The optical gain chip may include a reflective layer. Moreover, the SOI chip may include: a common optical waveguide, a splitter that splits the optical signal into optical signals, a first pair of resonators that are selectively optically coupled to the common optical waveguide and that are configured to perform modulation and filtering of the optical signals, and a first bus optical waveguide that is selectively optically coupled to the first pair of resonators. Furthermore, resonance wavelengths of the resonators may be offset from each other with a (e.g., fixed) separation approximately equal or corresponding to a modulation amplitude, and a reflectivity of the first pair of resonators may be approximately independent of the modulation.
    Type: Grant
    Filed: July 18, 2018
    Date of Patent: July 14, 2020
    Assignee: Axalume, Inc.
    Inventors: Ashok V. Krishnamoorthy, Jock Bovington, Xuezhe Zheng, Saman Saeedi
  • Patent number: 10620379
    Abstract: The present invention includes an optical waveguide with a grating and a method of making the same for increasing the effectiveness of the grating. In one example, the grating is at least partially covered by a liner layer disposed on at least a portion of a grating; and a cover layer disposed on the liner layer, wherein a first material selected for the core and ridges and a second material selected for the liner layer are selected to provide a difference in the index of refraction between the first and second material that is sufficient to provide a contrast therebetween.
    Type: Grant
    Filed: July 26, 2019
    Date of Patent: April 14, 2020
    Assignees: Southern Methodist University, Oracle International Corporation
    Inventors: Gary A. Evans, Jerome K. Butler, Jay B. Kirk, Ruo-Hua He, Jin Yao, Guoliang Li, Xuezhe Zheng, Ashok V. Krishnamoorthy
  • Patent number: 10620378
    Abstract: The present invention includes an optical waveguide with a grating and a method of making the same for increasing the effectiveness of the grating. In one example, the grating is at least partially covered by a liner layer disposed on at least a portion of a grating; and a cover layer disposed on the liner layer, wherein a first material selected for the core and ridges and a second material selected for the liner layer are selected to provide a difference in the index of refraction between the first and second material that is sufficient to provide a contrast therebetween.
    Type: Grant
    Filed: July 25, 2019
    Date of Patent: April 14, 2020
    Assignees: Southern Methodist University, Oracle International Corporation
    Inventors: Gary A. Evans, Jerome K. Butler, Jay B. Kirk, Ruo-Hua He, Jin Yao, Guoliang Li, Xuezhe Zheng, Ashok V. Krishnamoorthy
  • Patent number: 10591689
    Abstract: The disclosed embodiments provide an apparatus for connecting one or more optical fibers to an optoelectronic system. This apparatus includes a packaged optoelectronic module (POeM) comprising an optical connector, a silicon photonic (SiP) chip, an integrated circuit (IC) chip, at least one laser chip and a package substrate. The apparatus also includes an assembly adapter enclosing the POeM, wherein the assembly adapter includes a mechanical transfer (MT) ferrule cavity, which includes one or more coarse-alignment structures to guide an MT ferrule enclosing at least one optical fiber during assembly of the apparatus. The assembly adapter is comprised of a solder-reflow-compatible material to facilitate bonding the assembly adapter to a circuit board.
    Type: Grant
    Filed: February 6, 2017
    Date of Patent: March 17, 2020
    Assignee: Oracle International Corporation
    Inventors: Chaoqi Zhang, Hiren D. Thacker, Ivan Shubin, Xuezhe Zheng, Ashok V. Krishnamoorthy
  • Patent number: 10514502
    Abstract: A fabrication technique for cleaving a substrate in an integrated circuit is described. During this fabrication technique, a trench is defined on a back side of a substrate. For example, the trench may be defined using photoresist and/or a mask pattern on the back side of the substrate. The trench may extend from the back side to a depth less than a thickness of the substrate. Moreover, a buried-oxide layer and a semiconductor layer may be disposed on a front side of the substrate. In particular, the substrate may be included in a silicon-on-insulator technology. By applying a force proximate to the trench, the substrate may be cleaved to define a surface, such as an optical facet. This surface may have high optical quality and may extend across the substrate, the buried-oxide layer and the semiconductor layer.
    Type: Grant
    Filed: July 29, 2016
    Date of Patent: December 24, 2019
    Assignee: Oracle International Corporation
    Inventors: Jin-Hyoung Lee, Ivan Shubin, Xuezhe Zheng, Ashok V. Krishnamoorthy
  • Publication number: 20190353847
    Abstract: The present invention includes an optical waveguide with a grating and a method of making the same for increasing the effectiveness of the grating. In one example, the grating is at least partially covered by a liner layer disposed on at least a portion of a grating; and a cover layer disposed on the liner layer, wherein a first material selected for the core and ridges and a second material selected for the liner layer are selected to provide a difference in the index of refraction between the first and second material that is sufficient to provide a contrast therebetween.
    Type: Application
    Filed: July 26, 2019
    Publication date: November 21, 2019
    Inventors: Gary A. Evans, Jerome K. Butler, Jay B. Kirk, Ruo-Hua He, Jin Yao, Guoliang Li, Xuezhe Zheng, Ashok V. Krishnamoorthy
  • Publication number: 20190353846
    Abstract: The present invention includes an optical waveguide with a grating and a method of making the same for increasing the effectiveness of the grating. In one example, the grating is at least partially covered by a liner layer disposed on at least a portion of a grating; and a cover layer disposed on the liner layer, wherein a first material selected for the core and ridges and a second material selected for the liner layer are selected to provide a difference in the index of refraction between the first and second material that is sufficient to provide a contrast therebetween.
    Type: Application
    Filed: July 25, 2019
    Publication date: November 21, 2019
    Inventors: Gary A. Evans, Jerome K. Butler, Jay B. Kirk, Ruo-Hua He, Jin Yao, Guoliang Li, Xuezhe Zheng, Ashok V. Krishnamoorthy
  • Patent number: 10447013
    Abstract: A high-power packaged laser array that is thermal reflow compatible is described. Notably, a high-power III-V laser array is integrated on a silicon substrate with a matching array of ball lenses, an isolator and a coupler (such as a reflective layer) to achieve an edge-coupled or a surface-normal output laser array. In some embodiments, an isolator with a permanent magnet is used to preserve the magnetic domain or state of the isolator during the thermal reflow(s), which can involve temperatures up to 250 C. In order to relax the misalignment tolerance when integrating with the silicon chip, a laser array with a larger optical mode may be used to increase the output beam size. Moreover, a III-V laser array with an angled output optical waveguide can be used to improve the stability of the lasers at high power.
    Type: Grant
    Filed: July 18, 2018
    Date of Patent: October 15, 2019
    Assignee: Axalume, Inc.
    Inventors: Xuezhe Zheng, John E. Cunningham, Ashok V. Krishnamoorthy
  • Patent number: 10419128
    Abstract: An integrated circuit that includes an optical receiver is described. This integrated circuit may include an optical receiver. The optical receiver may include a photodiode that receives an optical signal and that outputs a corresponding current. Moreover, the optical receiver may include an inductor that is electrically coupled to the photodiode. Furthermore, the optical receiver may include a resistive analog front-end stage that is electrically coupled to the inductor. Note that the inductor may have a resistance per unit length that is greater than a first threshold value (such as 40 m?/?m), and the inductor may be approximately dispersion-less. For example, a Q factor for inductive peaking associated with the inductor is less than a second threshold value (such as 5).
    Type: Grant
    Filed: July 18, 2018
    Date of Patent: September 17, 2019
    Assignee: Axalume, Inc.
    Inventors: Saman Saeedi, Ashok V. Krishnamoorthy
  • Patent number: 10371898
    Abstract: The present invention includes an optical waveguide with a grating and a method of making the same for increasing the effectiveness of the grating. In one example, the grating is at least partially covered by a liner layer disposed on at least a portion of a grating; and a cover layer disposed on the liner layer, wherein a first material selected for the core and ridges and a second material selected for the liner layer are selected to provide a difference in the index of refraction between the first and second material that is sufficient to provide a contrast therebetween.
    Type: Grant
    Filed: September 5, 2014
    Date of Patent: August 6, 2019
    Assignee: Southern Methodist University
    Inventors: Gary A. Evans, Jerome K. Butler, Jay B. Kirk, Ruo-Hua He, Jin Yao, Guoliang Li, Xuezhe Zheng, Ashok V. Krishnamoorthy
  • Patent number: 10297981
    Abstract: The disclosed embodiments relate to the design of a hybrid laser comprising a shared ring mirror coupled to a pair of buses by a 3 dB coupler (also referred to as a “symmetric splitter”), which is described in more detail below. Each bus is also coupled to an array of ring filters, wherein each ring filter couples an associated reflective silicon optical amplifier (RSOA) to the shared ring mirror and in doing so forms a Verniered ring pair with the shared ring mirror. The resulting system provides a comb source with redundant channels that can provide individual outputs or a shared output. This hybrid laser provides a significant improvement over existing comb-based lasers by providing redundancy for at least one laser channel.
    Type: Grant
    Filed: October 13, 2016
    Date of Patent: May 21, 2019
    Assignee: Oracle International Corporation
    Inventors: Jock T. Bovington, Xuezhe Zheng, Ashok V. Krishnamoorthy
  • Patent number: 10281746
    Abstract: An optical transmitter includes a reflective semiconductor optical amplifier (RSOA) coupled to an input end of a first optical waveguide. An end of the first optical waveguide provides a transmitter output for the optical transmitter. Moreover, a section of the first optical waveguide between the input end and the output end is optically coupled to a ring modulator that modulates an optical signal based on an electrical input signal. A passive ring filter (or a 1×N silicon-photonic switch and a bank of band reflectors) is connected to provide a mirror that reflects light received from the second optical waveguide back toward the RSOA to form a lasing cavity. Moreover, the ring modulator and the passive ring filter have different sizes, which causes a Vernier effect that provides a large wavelength tuning range for the lasing cavity in response to tuning the ring modulator and the passive ring filter.
    Type: Grant
    Filed: September 5, 2018
    Date of Patent: May 7, 2019
    Assignee: Oracle International Corporation
    Inventors: Xuezhe Zheng, Ying Luo, Jin Yao, Ashok V. Krishnamoorthy
  • Patent number: 10222552
    Abstract: An integrated circuit is described. This integrated circuit includes an optical waveguide defined in a semiconductor layer, and a dielectric optical waveguide disposed on the semiconductor layer and that overlaps a region of the optical waveguide. Moreover, the dielectric optical waveguide includes an optical device (such as a mirror) on a facet separating a first portion of the dielectric optical waveguide and a second portion of the dielectric optical waveguide. The facet may be at an angle relative to a plane of the dielectric optical waveguide and may include a metal layer. During operation, an optical signal conveyed by the optical waveguide is evanescent coupled to the dielectric optical waveguide. Then, the optical signal may be reflected by the optical device. For example, the angle of the facet may be 45°, so that the optical signal is reflected normal to the plane of the dielectric optical waveguide.
    Type: Grant
    Filed: January 12, 2016
    Date of Patent: March 5, 2019
    Assignee: Oracle International Corporation
    Inventors: Stevan S. Djordjevic, Xuezhe Zheng, Ashok V. Krishnamoorthy
  • Patent number: 10205550
    Abstract: An optically switched network system includes an optical switch with N inputs and N outputs that connects N end-nodes and is structured to transmit N wavelengths from each of the N inputs to each of the N outputs. The system includes a virtual data plane and a virtual control plane, which both communicate through the optical switch. The virtual data plane provides any-to-all parallel connectivity for data transmissions among the N end-nodes. The N end-nodes are partitioned into two or more subsets, wherein end-nodes in a given source subset transmit data to a given destination subset using wavelengths, which are not used by end-nodes outside of the given source subset to transmit data to the same given destination subset. The virtual control plane includes two or more rings associated with the two or more subsets of end-nodes. Each ring passes through a subset of end-nodes, and is used to communicate arbitration information among arbitration logic located at each end-node in the ring.
    Type: Grant
    Filed: April 4, 2017
    Date of Patent: February 12, 2019
    Assignee: Oracle International Corporation
    Inventors: Shimon Muller, Ashok V. Krishnamoorthy, Leick D. Robinson, Xuezhe Zheng
  • Patent number: 10193636
    Abstract: A DC-coupled burst-mode optical receiver is described. The optical receiver may include an input node that receives a current, e.g., from an optoelectronic converter (such as a photodiode). Moreover, the optical receiver may include a current amplifier, coupled to the input node, that provides an output current based at least in part on the current, where the current amplifier has a shunt feedback path that reduces a bias sensitivity of the current amplifier and a feed-forward path that reduces a DC bias current of the current amplifier. Furthermore, the optical receiver may include a TIA, electrically coupled to the current amplifier, that converts the output current to an output voltage. Additionally, the optical receiver may include a feedback loop coupling an output of the TIA to an input of the feed-forward path.
    Type: Grant
    Filed: April 21, 2018
    Date of Patent: January 29, 2019
    Assignee: Axalume, Inc.
    Inventors: Saman Saeedi, Ashok V. Krishnamoorthy
  • Publication number: 20190027898
    Abstract: An optical source may include an optical gain chip that provides an optical signal and that is optically coupled to an SOI chip. The optical gain chip may include a reflective layer. Moreover, the SOI chip may include: a first optical waveguide, a first ring resonator that selectively optically coupled to a second optical waveguide and that performs phase modulation and filtering of the optical signal, the second optical waveguide, an amplitude modulator, and an output port. Note that the reflective layer in the optical gain chip and the amplitude modulator may define an optical cavity. Furthermore, a resonance of the first ring resonator may be aligned with a lasing wavelength, and the resonance of the first ring resonator and a resonance of the amplitude modulator may be offset from each other. Additionally, modulation of the first ring resonator and the amplitude modulator may be in-phase with each other.
    Type: Application
    Filed: July 18, 2018
    Publication date: January 24, 2019
    Applicant: Axalume, Inc.
    Inventors: Jock Bovington, Xuezhe Zheng, Saman Saeedi, Ashok V. Krishnamoorthy
  • Publication number: 20190028207
    Abstract: An integrated circuit that includes an optical receiver is described. This integrated circuit may include an optical receiver. The optical receiver may include a photodiode that receives an optical signal and that outputs a corresponding current. Moreover, the optical receiver may include an inductor that is electrically coupled to the photodiode. Furthermore, the optical receiver may include a resistive analog front-end stage that is electrically coupled to the inductor. Note that the inductor may have a resistance per unit length that is greater than a first threshold value (such as 40 m?/?m), and the inductor may be approximately dispersion-less. For example, a Q factor for inductive peaking associated with the inductor is less than a second threshold value (such as 5).
    Type: Application
    Filed: July 18, 2018
    Publication date: January 24, 2019
    Applicant: Axalume, Inc.
    Inventors: Saman Saeedi, Ashok V. Krishnamoorthy
  • Publication number: 20190027899
    Abstract: An optical source may include an optical gain chip that provides an optical signal and that is optically coupled to an SOI chip. The optical gain chip may include a reflective layer. Moreover, the SOI chip may include: a common optical waveguide, a splitter that splits the optical signal into optical signals, a first pair of resonators that are selectively optically coupled to the common optical waveguide and that are configured to perform modulation and filtering of the optical signals, and a first bus optical waveguide that is selectively optically coupled to the first pair of resonators. Furthermore, resonance wavelengths of the resonators may be offset from each other with a (e.g., fixed) separation approximately equal or corresponding to a modulation amplitude, and a reflectivity of the first pair of resonators may be approximately independent of the modulation.
    Type: Application
    Filed: July 18, 2018
    Publication date: January 24, 2019
    Applicant: Axalume, Inc.
    Inventors: Ashok V. Krishnamoorthy, Jock Bovington, Xuezhe Zheng, Saman Saeedi
  • Publication number: 20190027901
    Abstract: A high-power packaged laser array that is thermal reflow compatible is described. Notably, a high-power III-V laser array is integrated on a silicon substrate with a matching array of ball lenses, an isolator and a coupler (such as a reflective layer) to achieve an edge-coupled or a surface-normal output laser array. In some embodiments, an isolator with a permanent magnet is used to preserve the magnetic domain or state of the isolator during the thermal reflow(s), which can involve temperatures up to 250 C. In order to relax the misalignment tolerance when integrating with the silicon chip, a laser array with a larger optical mode may be used to increase the output beam size. Moreover, a III-V laser array with an angled output optical waveguide can be used to improve the stability of the lasers at high power.
    Type: Application
    Filed: July 18, 2018
    Publication date: January 24, 2019
    Applicant: Axalume, Inc.
    Inventors: Xuezhe Zheng, John E. Cunningham, Ashok V. Krishnamoorthy