Patents by Inventor Radhakrishnan L. Nagarajan

Radhakrishnan L. Nagarajan 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: 10826613
    Abstract: An integrated compact light engine configured in a on-board in-package optics assembly. The compact light engine includes a single substrate to integrate multiple optical-electrical modules. Each optical-electrical module includes an integrated optical transceiver based on silicon-photonics platform, in which a transmit path configured to output four light signals centered at four CWDM wavelengths and from four laser devices and to modulate the four light signals respectively by four modulators driven by a driver chipand to deliver a multiplexed transmission light. A receive path includes a photodetector to detect four input signals demultiplexed from an incoming light and a trans-impedance amplifier chip to process electrical signals converted from the four input signals detected. A multi-channel light engine is formed by co-integrating or co-mounting a switch device with multiple compact light engines on a common substrate member to provide up to 51.
    Type: Grant
    Filed: December 6, 2019
    Date of Patent: November 3, 2020
    Assignee: INPHI CORPORATION
    Inventors: Ding Liang, Mark Patterson, Roberto Coccioli, Radhakrishnan L. Nagarajan
  • Publication number: 20200343990
    Abstract: An integrated apparatus with optical/electrical interfaces and protocol converter on a single silicon substrate. The apparatus includes an optical module comprising one or more modulators respectively coupled with one or more laser devices for producing a first optical signal to an optical interface and one or more photodetectors for detecting a second optical signal from the optical interface to generate a current signal. Additionally, the apparatus includes a transmit lane module coupled between the optical module and an electrical interface to receive a first electric signal from the electrical interface and provide a framing protocol for driving the one or more modulators. Furthermore, the apparatus includes a receive lane module coupled between the optical module and the electrical interface to process the current signal to send a second electric signal to the electrical interface.
    Type: Application
    Filed: July 10, 2020
    Publication date: October 29, 2020
    Inventor: Radhakrishnan L. NAGARAJAN
  • Publication number: 20200341193
    Abstract: An coherent transceiver includes a single silicon photonics substrate configured to integrate a laser diode chip flip-mounted and coupled with a wavelength tuning section to provide a laser output with tuned wavelengths which is split in X:Y ratio partly into a coherent receiver block as local-oscillator signals and partly into a coherent transmitter block as a light source. The coherent receiver includes a polarization-beam-splitter-rotator to split a coherent input signal to a TE-mode signal and a TM*-mode signal respectively detected by two 90-deg hybrid receivers and a flip-mounted TIA chip assisted by two local-oscillator signals from the tunable laser device.
    Type: Application
    Filed: July 14, 2020
    Publication date: October 29, 2020
    Inventor: Radhakrishnan L. NAGARAJAN
  • Publication number: 20200327093
    Abstract: The present invention provides an optical module for communicating a peer to peer transaction to transmit cryptocurrency. The optical module includes a substrate, a memory resource formed on the substrate, and a cryptocurrency wallet provided on the memory resource. Additionally, the optical module includes an optical communication block configured to generate an optical signal based on an electrical signal carrying a transaction message about an order of executing a plurality of transactions of cryptocurrency. The optical module includes an internal encryption block for encrypting the optical signal in the quadrature phases using an optical Quantum Key Generation encryption protocol.
    Type: Application
    Filed: June 25, 2020
    Publication date: October 15, 2020
    Inventor: Radhakrishnan L. NAGARAJAN
  • Patent number: 10788638
    Abstract: A silicon-based edge coupler for coupling a fiber with a waveguide includes a cantilever member being partially suspended with its anchored end coupled to a silicon photonics die in a first part of a silicon substrate and a free end terminated near an edge region separating a second part of the silicon substrate from the first part. The edge coupler further includes a mechanical stopper formed at the edge region with a gap distance ahead of the free end of the cantilever member. Additionally, a V-groove is formed in the second part of the silicon substrate characterized by a top opening and a bottom plane symmetrically connected by two sloped side walls along a fixed Si-crystallography angle. The V-groove is configured to support a fiber with an end facet being pushed against the mechanical stopper and a core center being aligned with the free end of the cantilever member.
    Type: Grant
    Filed: January 10, 2019
    Date of Patent: September 29, 2020
    Assignee: INPHI CORPORATION
    Inventors: Radhakrishnan L. Nagarajan, Masaki Kato
  • Publication number: 20200301071
    Abstract: An coherent transceiver includes a single silicon photonics substrate configured to integrate a laser diode chip flip-mounted and coupled with a wavelength tuning section to provide a laser output with tuned wavelengths which is split in X:Y ratio partly into a coherent receiver block as local-oscillator signals and partly into a coherent transmitter block as a light source. The coherent receiver includes a polarization-beam-splitter-rotator to split a coherent input signal to a TE-mode signal and a TM*-mode signal respectively detected by two 90-deg hybrid receivers and a flip-mounted TIA chip assisted by two local-oscillator signals from the tunable laser device.
    Type: Application
    Filed: April 7, 2020
    Publication date: September 24, 2020
    Inventor: Radhakrishnan L. NAGARAJAN
  • Publication number: 20200301070
    Abstract: An coherent transceiver includes a single silicon photonics substrate configured to integrate a laser diode chip flip-mounted and coupled with a wavelength tuning section to provide a laser output with tuned wavelengths which is split in X:Y ratio partly into a coherent receiver block as local-oscillator signals and partly into a coherent transmitter block as a light source. The coherent receiver includes a polarization-beam-splitter-rotator to split a coherent input signal to a TE-mode signal and a TM*-mode signal respectively detected by two 90-deg hybrid receivers and a flip-mounted TIA chip assisted by two local-oscillator signals from the tunable laser device.
    Type: Application
    Filed: April 7, 2020
    Publication date: September 24, 2020
    Inventor: Radhakrishnan L. NAGARAJAN
  • Patent number: 10779063
    Abstract: In an example, the present invention includes an integrated system on chip device. The device has a variable bias block configured with the control block, the variable bias block being configured to selectively tune each of a plurality of laser devices provided on the silicon photonics device to adjust for at least a wavelength of operation, a fabrication tolerance, and an extinction ratio.
    Type: Grant
    Filed: July 14, 2017
    Date of Patent: September 15, 2020
    Assignee: INPHI CORPORATION
    Inventor: Radhakrishnan L. Nagarajan
  • Patent number: 10754091
    Abstract: An coherent transceiver includes a single silicon photonics substrate configured to integrate a laser diode chip flip-mounted and coupled with a wavelength tuning section to provide a laser output with tuned wavelengths which is split in X:Y ratio partly into a coherent receiver block as local-oscillator signals and partly into a coherent transmitter block as a light source. The coherent receiver includes a polarization-beam-splitter-rotator to split a coherent input signal to a TE-mode signal and a TM*-mode signal respectively detected by two 90-deg hybrid receivers and a flip-mounted TIA chip assisted by two local-oscillator signals from the tunable laser device.
    Type: Grant
    Filed: March 18, 2019
    Date of Patent: August 25, 2020
    Assignee: INPHI CORPORATION
    Inventor: Radhakrishnan L. Nagarajan
  • Publication number: 20200266899
    Abstract: The present invention is directed to communication systems and methods. In a specific embodiment, the present invention provides an optical receiver that receives a data stream from an optical transmitter. The optical receiver determines a histogram contour parameter using the data stream and inserts the histogram contour parameter into a back-channel data segment, which is then transmitted to the optical transmitter. The optical transmitter changes its data transmission setting based on the histogram contour parameter. There are other embodiments as well.
    Type: Application
    Filed: March 24, 2020
    Publication date: August 20, 2020
    Inventors: Todd ROPE, Hari SHANKAR, Radhakrishnan L. NAGARAJAN
  • Patent number: 10749622
    Abstract: An integrated apparatus with optical/electrical interfaces and protocol converter on a single silicon substrate. The apparatus includes an optical module comprising one or more modulators respectively coupled with one or more laser devices for producing a first optical signal to an optical interface and one or more photodetectors for detecting a second optical signal from the optical interface to generate a current signal. Additionally, the apparatus includes a transmit lane module coupled between the optical module and an electrical interface to receive a first electric signal from the electrical interface and provide a framing protocol for driving the one or more modulators. Furthermore, the apparatus includes a receive lane module coupled between the optical module and the electrical interface to process the current signal to send a second electric signal to the electrical interface.
    Type: Grant
    Filed: March 9, 2020
    Date of Patent: August 18, 2020
    Assignee: INPHI CORPORATION
    Inventor: Radhakrishnan L. Nagarajan
  • Publication number: 20200257050
    Abstract: An optical dispersion compensator integrated with a silicon photonics system including a first phase-shifter coupled to a second phase-shifter in parallel on the silicon substrate characterized in an athermal condition. The dispersion compensator further includes a third phase-shifter on the silicon substrate to the first phase-shifter and the second phase-shifter through two 2×2 splitters to form an optical loop. A second entry port of a first 2×2 splitter is for coupling with an input fiber and a second exit port of a second 2×2 splitter is for coupling with an output fiber. The optical loop is characterized by a total phase delay tunable via each of the first phase-shifter, the second phase-shifter, and the third phase-shifter such that a normal dispersion (>0) at a certain wavelength in the input fiber is substantially compensated and independent of temperature.
    Type: Application
    Filed: March 30, 2020
    Publication date: August 13, 2020
    Inventors: Xiaoguang TU, Radhakrishnan L. NAGARAJAN, Masaki KATO
  • Patent number: 10733138
    Abstract: The present invention provides an integrated system-on-chip device. The device is configured on a single silicon substrate member. The device has a data input/output interface provided on the substrate member. The device has an input/output block provided on the substrate member and coupled to the data input/output interface. The device has a signal processing block provided on the substrate member and coupled to the input/output block. The device has a driver module provided on the substrate member and coupled to the signal processing block. The device further includes a driver interface and coupled to the driver module and configured to be coupled to a silicon photonics device. In an example, a control block is configured to receive and send instruction(s) in a digital format to the communication block and is configured to receive and send signals in an analog format to communicate with the silicon photonics device.
    Type: Grant
    Filed: November 20, 2018
    Date of Patent: August 4, 2020
    Assignee: INPHI CORPORATION
    Inventor: Radhakrishnan L. Nagarajan
  • Publication number: 20200242073
    Abstract: The present invention includes an integrated system-on-chip device configured on a substrate member. The device has a data input/output interface provided on the substrate member and configured for a predefined data rate and protocol. The device has an input/output block provided on the substrate member and coupled to the data input/output interface. The input/output block comprises a SerDes block, a CDR block, a compensation block, and an equalizer block. The SerDes block is configured to convert a first data stream of N having a first predefined data rate at a first clock rate into a second data stream of M having a second predefined data rate at a second clock rate. The device has a driver module provided on the substrate member and coupled to a signal processing block, and a driver interface provided on the substrate member and coupled to the driver module and a silicon photonics device.
    Type: Application
    Filed: April 9, 2020
    Publication date: July 30, 2020
    Inventors: Radhakrishnan L. NAGARAJAN, Chao XU
  • Publication number: 20200225429
    Abstract: A silicon-based edge coupler for coupling a fiber with a waveguide includes a cantilever member being partially suspended with its anchored end coupled to a silicon photonics die in a first part of a silicon substrate and a free end terminated near an edge region separating a second part of the silicon substrate from the first part. The edge coupler further includes a mechanical stopper formed at the edge region with a gap distance ahead of the free end of the cantilever member. Additionally, a V-groove is formed in the second part of the silicon substrate characterized by a top opening and a bottom plane symmetrically connected by two sloped side walls along a fixed Si-crystallography angle. The V-groove is configured to support a fiber with an end facet being pushed against the mechanical stopper and a core center being aligned with the free end of the cantilever member.
    Type: Application
    Filed: January 10, 2019
    Publication date: July 16, 2020
    Inventors: Radhakrishnan L. NAGARAJAN, Masaki KATO
  • Patent number: 10715255
    Abstract: The present invention relates to telecommunication techniques and integrated circuit (IC) devices. More specifically, embodiments of the present invention provide an off-quadrature modulation system. Once an off-quadrature modulation position is determined, a ratio between DC power transfer amplitude and dither tone amplitude for a modulator is as a control loop target to stabilize off-quadrature modulation. DC power transfer amplitude is obtained by measuring and sampling the output of an optical modulator. Dither tone amplitude is obtained by measuring and sampling the modulator output and performing calculation using the optical modulator output values and corresponding dither tone values. There are other embodiments as well.
    Type: Grant
    Filed: August 8, 2019
    Date of Patent: July 14, 2020
    Assignee: INPHI CORPORATION
    Inventors: Todd Rope, Radhakrishnan L. Nagarajan, Hari Shankar
  • Publication number: 20200212651
    Abstract: A tunable laser device based on silicon photonics includes a substrate configured with a patterned region comprising one or more vertical stoppers, an edge stopper facing a first direction, a first alignment feature structure formed in the patterned region along the first direction, and a bond pad disposed between the vertical stoppers. Additionally, the tunable laser includes an integrated coupler built in the substrate located at the edge stopper and a laser diode chip including a gain region covered by a P-type electrode and a second alignment feature structure formed beyond the P-type electrode. The laser diode chip is flipped to rest against the one or more vertical stoppers with the P-type electrode attached to the bond pad and the gain region coupled to the integrated coupler. Moreover, the tunable laser includes a tuning filter fabricated in the substrate and coupled via a wire waveguide to the integrated coupler.
    Type: Application
    Filed: March 13, 2020
    Publication date: July 2, 2020
    Inventors: Radhakrishnan L. NAGARAJAN, Masaki KATO, Nourhan EID, Kenneth Ling WONG
  • Publication number: 20200213025
    Abstract: An integrated apparatus with optical/electrical interfaces and protocol converter on a single silicon substrate. The apparatus includes an optical module comprising one or more modulators respectively coupled with one or more laser devices for producing a first optical signal to an optical interface and one or more photodetectors for detecting a second optical signal from the optical interface to generate a current signal. Additionally, the apparatus includes a transmit lane module coupled between the optical module and an electrical interface to receive a first electric signal from the electrical interface and provide a framing protocol for driving the one or more modulators. Furthermore, the apparatus includes a receive lane module coupled between the optical module and the electrical interface to process the current signal to send a second electric signal to the electrical interface.
    Type: Application
    Filed: March 9, 2020
    Publication date: July 2, 2020
    Inventor: Radhakrishnan L. NAGARAJAN
  • Publication number: 20200183105
    Abstract: A photonic transceiver apparatus in QSFP package. The apparatus includes a case having a base member, two partial side members, and a lid member to provide a spatial volume with an opening at a back end of the base member. Additionally, the apparatus includes a PCB, installed inside the spatial volume over the base member having a pluggable electrical connector at the back end. Further, the apparatus includes multiple optical transmitting devices in mini-transmit-optical-sub-assembly package, each being mounted on a common support structure and having a laser output port in reversed orientation toward the back end. Furthermore, the apparatus includes a silicon photonics chip, including a fiber-to-silicon attachment module, mounted on the PCB and coupled to a modulation driver module and a trans-impedance amplifier module. Moreover, the apparatus includes a pair of optical input/output ports being back connected to the fiber-to-silicon attachment module.
    Type: Application
    Filed: February 18, 2020
    Publication date: June 11, 2020
    Inventors: Radhakrishnan L. NAGARAJAN, Peng-Chih LI, Masaki KATO
  • Publication number: 20200152574
    Abstract: A method for forming a silicon photonics interposer having through-silicon vias (TSVs). The method includes forming vias in a front side of a silicon substrate and defining primary structures for forming optical devices in the front side. Additionally, the method includes bonding a first handle wafer to the front side and thinning down the silicon substrate from the back side and forming bumps at the back side to couple with a conductive material in the vias. Furthermore, the method includes bonding a second handle wafer to the back side and debonding the first handle wafer from the front side to form secondary structures based on the primary structures. Moreover, the method includes forming pads at the front side to couple with the bumps at the back side before completing final structures based on the secondary structures and debonding the second handle wafer from the back side.
    Type: Application
    Filed: January 9, 2020
    Publication date: May 14, 2020
    Inventors: Liang DING, Radhakrishnan L. NAGARAJAN