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).

  • 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: 20190004340
    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: Application
    Filed: September 5, 2018
    Publication date: January 3, 2019
    Applicant: Oracle International Corporation
    Inventors: Xuezhe Zheng, Ying Luo, Jin Yao, Ashok V. Krishnamoorthy
  • 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
  • Patent number: 10162199
    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: November 21, 2016
    Date of Patent: December 25, 2018
    Assignee: Oracle International Corporation
    Inventors: Xuezhe Zheng, Ying Luo, Jin Yao, Ashok V. Krishnamoorthy
  • Patent number: 10120211
    Abstract: An optical transmitter includes: a set of reflective silicon optical amplifiers (RSOAs), a set of ring modulators, a shared broadband reflector, a set of intermediate waveguides, and a shared waveguide. Each intermediate waveguide channels light from an RSOA in proximity to an associated ring modulator to cause optically coupled light to circulate in the associated ring modulator. The shared waveguide is coupled to the shared broadband reflector, and passes in proximity to the set of ring modulators, so that light circulating in each ring modulator causes optically coupled light to flow in the shared optical waveguide. During operation, each RSOA forms a lasing cavity with the shared broadband reflector, wherein each lasing cavity has a different wavelength, which is determined by a resonance of the associated ring modulator. The different wavelengths are combined in the shared waveguide to produce a combined output.
    Type: Grant
    Filed: November 8, 2016
    Date of Patent: November 6, 2018
    Assignee: Oracle International Corporation
    Inventors: Xuezhe Zheng, Ying Luo, Ashok V. Krishnamoorthy
  • Patent number: 10119857
    Abstract: An integrated optical device includes a photo-detector (such as germanium) optically coupled to an optical waveguide. This photo-detector is deposited on the optical waveguide, and an optical signal propagating in the optical waveguide may be evanescently coupled to the photo-detector. In order to increase the absorption length of the photo-detector, a mirror (such as a distributed Bragg reflection grating) is included in the optical waveguide near the end of the photo-detector. This mirror reflects the optical signal back toward the photo-detector, thereby increasing the absorption of the optical signal by the photo-detector. In addition, absorption may be reduced by using electrical contacts that are electrically coupled to the photo-detector at locations where the optical mode of the optical signal is largely in the underlying optical waveguide, and by using a fingered metal layer to couple to the electrical contacts.
    Type: Grant
    Filed: August 17, 2012
    Date of Patent: November 6, 2018
    Assignee: ORACLE INTERNATIONAL CORPORATION
    Inventors: Guoliang Li, Xuezhe Zheng, Ying L. Luo, Ashok V. Krishnamoorthy
  • Publication number: 20180287729
    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: Application
    Filed: April 4, 2017
    Publication date: October 4, 2018
    Applicant: Oracle International Corporation
    Inventors: Shimon Muller, Ashok V. Krishnamoorthy, Leick D. Robinson, Xuezhe Zheng
  • Patent number: 10090645
    Abstract: An integrated laser that provides multiple outputs includes a reflective silicon optical amplifier (RSOA) having a reflective end with a reflective coating and an interface end. It also includes an optical waveguide optically coupled to the RSOA. A distributed-Bragg-reflector (DBR) ring resonator is also optically coupled to the optical waveguide, wherein the DBR ring resonator partially reflects a wavelength of the optical signal from the optical waveguide, thereby causing balanced light to flow in clockwise and counter-clockwise directions inside the DBR ring resonator. The integrated laser additionally includes an output waveguide having 2*N ends that function as two outputs, wherein the output waveguide is optically coupled to the DBR ring resonator, which causes balanced light to flow in two directions in the output waveguide, thereby causing the 2*N outputs to provide balanced power.
    Type: Grant
    Filed: June 23, 2016
    Date of Patent: October 2, 2018
    Assignee: Oracle International Corporation
    Inventors: Jock T. Bovington, Xuezhe Zheng, Ashok V. Krishnamoorthy
  • Publication number: 20180267265
    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: Application
    Filed: February 6, 2017
    Publication date: September 20, 2018
    Applicant: Oracle International Corporation
    Inventors: Chaoqi Zhang, Hiren D. Thacker, Ivan Shubin, Xuezhe Zheng, Ashok V. Krishnamoorthy
  • Publication number: 20180270551
    Abstract: The disclosed embodiments provide an optically switched network system. This system includes a passive optical switch with N inputs and N outputs, which can communicate different wavelengths from each of the N inputs to each of the N outputs. It also includes N end-nodes, and N pairs of optical fibers, wherein each pair connects one of the N end-nodes to one of the N inputs and one of the N outputs. The optically switched network is organized into a virtual data plane and a virtual control plane, which both communicate through the same underlying physical network. The virtual data plane provides any-to-all parallel connectivity for data transmissions among the N end-nodes. The virtual control plane is organized as a ring that serially connects the N end-nodes, wherein the ring communicates arbitration information among distributed-arbitration logic at each of the N end-nodes.
    Type: Application
    Filed: March 15, 2017
    Publication date: September 20, 2018
    Applicant: Oracle International Corporation
    Inventors: Ashok V. Krishnamoorthy, Shimon Muller, Xuezhe Zheng
  • Publication number: 20180261983
    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: Application
    Filed: October 13, 2016
    Publication date: September 13, 2018
    Applicant: Oracle International Corporation
    Inventors: Jock T. Bovington, Xuezhe Zheng, Ashok V. Krishnamoorthy
  • Publication number: 20180231808
    Abstract: An optical transmitter includes: a set of reflective silicon optical amplifiers (RSOAs), a set of ring modulators, a shared broadband reflector, a set of intermediate waveguides, and a shared waveguide. Each intermediate waveguide channels light from an RSOA in proximity to an associated ring modulator to cause optically coupled light to circulate in the associated ring modulator. The shared waveguide is coupled to the shared broadband reflector, and passes in proximity to the set of ring modulators, so that light circulating in each ring modulator causes optically coupled light to flow in the shared optical waveguide. During operation, each RSOA forms a lasing cavity with the shared broadband reflector, wherein each lasing cavity has a different wavelength, which is determined by a resonance of the associated ring modulator. The different wavelengths are combined in the shared waveguide to produce a combined output.
    Type: Application
    Filed: November 8, 2016
    Publication date: August 16, 2018
    Applicant: Oracle International Corporation
    Inventors: Xuezhe Zheng, Ying Luo, Ashok V. Krishnamoorthy
  • 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
  • Publication number: 20180191137
    Abstract: An integrated laser that provides multiple outputs includes a reflective silicon optical amplifier (RSOA) having a reflective end with a reflective coating and an interface end. It also includes an optical waveguide optically coupled to the RSOA. A distributed-Bragg-reflector (DBR) ring resonator is also optically coupled to the optical waveguide, wherein the DBR ring resonator partially reflects a wavelength of the optical signal from the optical waveguide, thereby causing balanced light to flow in clockwise and counter-clockwise directions inside the DBR ring resonator. The integrated laser additionally includes an output waveguide having 2*N ends that function as two outputs, wherein the output waveguide is optically coupled to the DBR ring resonator, which causes balanced light to flow in two directions in the output waveguide, thereby causing the 2*N outputs to provide balanced power.
    Type: Application
    Filed: June 23, 2016
    Publication date: July 5, 2018
    Applicant: Oracle International Corporation
    Inventors: Jock T. Bovington, Xuezhe Zheng, Ashok V. Krishnamoorthy
  • Patent number: 10014659
    Abstract: An optical source is described. This optical source includes a set of semiconductor optical amplifiers, with a semiconductor other than silicon, which provides an optical gain medium. In addition, a photonic chip, optically coupled to the set of semiconductor optical amplifiers, includes optical paths. Each of the optical paths includes an optical waveguide and a distributed-Bragg-reflector (DBR) ring resonator. The DBR ring resonator at least partially reflects a given tunable wavelength in an optical signal provided by a given semiconductor optical amplifier. Moreover, the DBR ring resonator includes a different number of grating periods than DBR ring resonators in the remaining optical paths, and the DBR ring resonators in the optical paths have a common radius.
    Type: Grant
    Filed: June 15, 2016
    Date of Patent: July 3, 2018
    Assignee: Oracle International Corporation
    Inventors: Jock Bovington, Xuezhe Zheng, Ashok V. Krishnamoorthy
  • Publication number: 20180180808
    Abstract: The disclosed embodiments relate to an optoelectronic module, comprising one or more optical chips, and a molded substrate, which is molded around the one or more optical chips, so that the one or more optical chips are embedded in the molded substrate, and an active surface of each optical chip remains exposed. This molded substrate includes one or more through vias that provide electrical signal paths through the molded substrate. After the molded substrate is fabricated, one or more integrated circuit (IC) chips can be flip-mounted to the molded substrate and electrically connected to the one or more embedded optical chips and the one or more through vias. Also, one or more optical connectors containing optical waveguides can be flip-mounted on the molded substrate and optically coupled to the one or more embedded optical chips.
    Type: Application
    Filed: December 22, 2016
    Publication date: June 28, 2018
    Applicant: Oracle International Corporation
    Inventors: Chaoqi Zhang, Hiren D. Thacker, Ashok V. Krishnamoorthy
  • Patent number: 9983420
    Abstract: In the optical device, a ring-resonator modulator, having an adjustable resonance (center) wavelength, optically couples an optical signal that includes the carrier wavelength from an input optical waveguide to an output optical waveguide. A monitoring mechanism in the optical device, which is optically coupled to the output optical waveguide, monitors a performance metric of an output optical signal from the output waveguide. For example, the monitoring mechanism may monitor: an average optical power associated with the output optical signal, and/or an amplitude of the output optical signal. Moreover, control logic in the optical device adjusts the resonance wavelength based on the monitored performance metric so that the performance metric is optimized.
    Type: Grant
    Filed: October 16, 2014
    Date of Patent: May 29, 2018
    Assignee: ORACLE INTERNATIONAL CORPORATION
    Inventors: Philip Amberg, Eric Y. Chang, Xuezhe Zheng, Frankie Y. Liu, Ronald Ho, Ashok V. Krishnamoorthy
  • Patent number: 9983359
    Abstract: An integrated circuit that includes a wavelength-filter layer stack (which may include silicon oxynitride) and an optical substrate (such as a silicon-on-insulator platform) is described. During operation, an optical signal received from an optical fiber or an optical waveguide is wavelength filtered into a set of wavelength-filter optical waveguides by an optical multiplexer/demultiplexer (such as an Echelle grating and/or an array waveguide grating) in the wavelength-filter layer stack. Then, wavelength-filtered optical signals are optically coupled to the optical substrate, where they are received using photodetectors. Alternatively, modulators in the optical substrate modulate wavelength-filtered modulated optical signals, which are then optically coupled to the set of wavelength-filter optical waveguides in the wavelength-filter layer stack.
    Type: Grant
    Filed: August 24, 2017
    Date of Patent: May 29, 2018
    Assignee: Oracle International Corporation
    Inventors: Ying Luo, Xuezhe Zheng, Jin Yao, Ashok V. Krishnamoorthy
  • Publication number: 20180143461
    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: Application
    Filed: November 21, 2016
    Publication date: May 24, 2018
    Applicant: Oracle International Corporation
    Inventors: Xuezhe Zheng, Ying Luo, Jin Yao, Ashok V. Krishnamoorthy
  • Patent number: 9967049
    Abstract: A transceiver separates wavelength-division-multiplexing (WDM) components into two groups, one of which is more sensitive to temperature than the other group. The temperature-sensitive group of optical components is implemented on a first substrate in the transceiver that has a lower thermo-optic coefficient than a second substrate in the transceiver, which contains the group of optical components that is less temperature sensitive. In particular, the first substrate, which may be glass, may include WDM components that convey optical signals having multiple carrier wavelengths. Moreover, the second substrate, such as a silicon substrate (e.g., a silicon-on-insulator platform), may include multiple parallel optical paths with optical components, in which a given optical path conveys an optical signal having a given carrier wavelength.
    Type: Grant
    Filed: April 28, 2016
    Date of Patent: May 8, 2018
    Assignee: Oracle International Corporation
    Inventors: Xuezhe Zheng, Ashok V. Krishnamoorthy