Carlsbad, CA, United States
Carlsbad, CA, United States

Luxtera Inc., founded in 2001, is based in Carlsbad, California. Luxtera is a fabless semiconductor company that is using silicon photonics technology to build complex electro-optical systems in a production silicon CMOS process. It is the first company on the market with a product that monolithically incorporates active optics for data communications manufactured with low-cost silicon-based chip processing.This class of technology is widely predicted to displace large portions of the existing photonics industry that rely on discrete assemblies of electronic and photonic devices. Luxtera's partners include Freescale Semiconductor . Luxtera is a Caltech spin-out with funding from venture capital, its business partners, and DARPA. It was founded by a number of members of Prof. Axel Scherer's lab group, including Cary Gunn, Michael Hochberg, Tom Baehr-Jones, and also Axel Scherer. Other co-founders include Prof. Eli Yablonovitch and John Oxaal.In 2010, Luxtera was selected as one of MIT Technology Review's 50 Most Innovative Companies. Wikipedia.


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Methods and systems for partial integration of wavelength division multiplexing and bi-directional solutions are disclosed and may include, an optical transceiver on a silicon photonics integrated circuit coupled to a planar lightwave circuit (PLC). The silicon photonics integrated circuit may include a first modulator and first light source that operates at a first wavelength and a second modulator and second light source that operates at a second wavelength. The transceiver and PLC are operable to modulate a first continuous wave (CW) optical signal from the first light source utilizing the first modulator driven by a first electrical signal and modulate a second CW optical signal from the second light source utilizing the second modulator driven by a second electrical signal. The modulated signals may be communicated from the modulators to the PLC utilizing a first pair of grating couplers in the IC and combined in the PLC.


A system for a feedback transimpedance amplifier with sub-40 khz low-frequency cutoff is disclosed and may include amplifying electrical signals received via coupling capacitors utilizing a transimpedance amplifier (TIA) having feedback paths comprising source followers and feedback resistors. The feedback paths may be coupled prior to the coupling capacitors at inputs of the TIA. Voltages may be level shifted prior to the coupling capacitors to ensure stable bias conditions for the TIA. The TIA may be integrated in a CMOS chip and the source followers may comprise CMOS transistors. The TIA may receive current-mode logic or voltage signals. The electrical signals may be received from a photodetector, which may comprise a silicon germanium photodiode and may be differentially coupled to the TIA. The chip may comprise a CMOS photonics chip where optical signals for the photodetector in the CMOS photonics chip may be received via one or more optical fibers.


Methods and systems for grating couplers incorporating perturbed waveguides are disclosed and may include in a semiconductor photonics die, communicating optical signals into and/or out of the die utilizing a grating coupler on the die, where the grating coupler comprises perturbed waveguides. The perturbed waveguides may include rows of continuous waveguides with non-discrete scatterers extending throughout a length of said perturbed waveguides a variable width along their length. The grating coupler may comprise a single polarization grating coupler comprising perturbed waveguides and a non-perturbed grating. The grating coupler may comprise a polarization splitting grating coupler (PSGC) that includes two sets of perturbed waveguides at a non-zero angle, or a plurality of non-linear rows of discrete shapes. The PSGC may comprise discrete scatterers at an intersection of the sets of perturbed waveguides. The grating coupler may comprise individual scatterers between the perturbed waveguides.


A method and system for coupling optical signals into silicon optoelectronic chips are disclosed and may include coupling one or more optical signals into a back surface of a CMOS photonic chip comprising photonic, electronic, and optoelectronic devices. The devices may be integrated in a front surface of the chip and one or more optical couplers may receive the optical signals in the front surface of the chip. The optical signals may be coupled into the back surface of the chip via one or more optical fibers and/or optical source assemblies. The optical signals may be coupled to the grating couplers via a light path etched in the chip, which may be refilled with silicon dioxide. The chip may be flip-chip bonded to a packaging substrate. Optical signals may be reflected back to the grating couplers via metal reflectors, which may be integrated in dielectric layers on the chip.


Patent
Luxtera | Date: 2016-08-08

A system for integrated power combiners is disclosed and may include receiving optical signals in input optical waveguides and phase-modulating the signals to configure a phase offset between signals received at a first optical coupler, where the first optical coupler may generate output signals having substantially equal optical powers. Output signals of the first optical coupler may be phase-modulated to configure a phase offset between signals received at a second optical coupler, which may generate an output signal having an optical power of essentially zero and a second output signal having a maximized optical power. Optical signals received by the input optical waveguides may be generated utilizing a polarization-splitting grating coupler to enable polarization-insensitive combining of optical signals. Optical power may be monitored using optical detectors. The monitoring of optical power may be used to determine a desired phase offset between the signals received at the first optical coupler.


Methods and systems for process and temperature compensation in a transimpedance amplifier using a dual replica and servo loop is disclosed and may include a transimpedance amplifier (TIA) circuit comprising a first TIA, a second TIA, a third TIA, and a control loop. The first TIA comprises a fixed feedback resistance and the second and third TIAs each comprise a configurable feedback impedance. The control loop comprises a gain stage with inputs coupled to outputs of the first and second TIAs and with an output coupled to the configurable feedback impedance of the second and third TIAs. The circuit may be operable to configure a gain level of the first TIA based on the fixed feedback resistance and a reference current applied at an input to the first TIA, and configure a gain level of the second and third TIAs based on a control voltage generated by the gain stage.


Methods and systems for accurate gain adjustment of a transimpedance amplifier using a dual replica and servo loop is disclosed and may include, in a transimpedance amplifier (TIA) circuit comprising a first TIA, a second TIA, and a third TIA, each comprising a configurable feedback impedance, and a control loop, where the control loop comprises a gain stage with inputs coupled to outputs of the first and second TIAs and an output coupled to the configurable feedback impedance of the second and third TIAs: configuring a gain level of the first TIA by configuring its feedback impedance, configuring a gain level of the third TIA by configuring a reference current applied to an input of the first TIA, and amplifying a received electrical signal to generate an output voltage utilizing the third TIA. The reference current may generate a reference voltage at one of the inputs of the gain stage.


A method and system for optoelectronic receivers utilizing waveguide heterojunction phototransistors (HPTs) integrated in a wafer are disclosed and may include receiving optical signals via optical fibers operably coupled to a top surface of the chip. Electrical signals may be generated utilizing HPTs that detect the optical signals. The electrical signals may be amplified via voltage amplifiers, or transimpedance amplifiers, the outputs of which may be utilized to bias the HPTs by a feedback network. The optical signals may be coupled into opposite ends of the HPTs. A collector of the HPTs may comprise a silicon layer and a germanium layer, a base may comprise a silicon germanium alloy with germanium composition ranging from 70% to 100%, and an emitter including crystalline or poly Si or SiGe. The optical signals may be demodulated by communicating a mixer signal to a base terminal of the HPTs.


Methods and systems for large silicon photonic interposers by stitching are disclosed and may include, in an integrated optical communication system including CMOS electronics die coupled to a silicon photonic interposer, where the interposer includes a plurality of reticle sections: communicating an optical signal between two of the plurality of reticle sections utilizing a waveguide. The waveguide may include a taper region at a boundary between the two reticle sections, the taper region expanding an optical mode of the communicated optical signal prior to the boundary and narrowing the optical mode after the boundary. A continuous wave (CW) optical signal may be received in a first of the reticle sections from an optical source external to the interposer. The CW optical signal may be received in the interposer from an optical source assembly coupled to a grating coupler in the first of the reticle sections in the silicon photonic interposer.


Methods and systems for an optical connection service interface may include, in an optical data link comprising an optical fiber, a local control system, first and second transceivers at ends of the optical fiber, generating a control signal for the local control system at a low frequency and communicating, utilizing the optical fiber, an optical data signal at a high frequency and an optical service signal for an Optical Connection Service interface (OCSi) at an intermediate frequency. An optical signal may be modulated at the intermediate frequencies for the OCSi, and may be modulated and communicated to the second transceiver. The communicated modulated signal and the optical data signal may be detected utilizing a photodetector in the second transceiver. The detected optical signal may be demodulated, and an optical power of the optical data signal may be configured based on the demodulated signal.

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