Abstract: Methods and systems for a chip-on-wafer-on-substrate assembly are disclosed and may include in an optical communication system comprising an electronics die and a substrate. The electronics die is bonded to a first surface of a photonic interposer and the substrate is coupled to a second surface of the photonic interposer opposite to the first surface. An optical fiber and a light source assembly are coupled to the second surface of the interposer in one or more cavities formed in the substrate. A continuous wave (CW) optical signal may be received in the photonic interposer from the light source assembly, and a modulated optical signal may be communicated between the optical fiber and photonic interposer. The received CW optical signal may be coupled to an optical waveguide in the photonic interposer using a grating coupler.

Abstract: Methods and systems for split voltage domain transmitter circuits are disclosed and may include a two-branch output stage including a plurality of CMOS transistors, each branch of the two-branch output stage comprising two stacked CMOS inverter pairs from among the plurality of CMOS transistors; the two stacked CMOS inverter pairs of a given branch being configured to drive a respective load, in phase opposition to the other branch; and a pre-driver circuit configured to receive a differential modulating signal and output, to respective inputs of the two stacked CMOS inverters, two synchronous differential voltage drive signals having a swing of half the supply voltage and being DC-shifted by half of the supply voltage with respect to each other. The load may include a series of diodes that are driven in differential mode via the drive signals. An optical signal may be modulated via the diodes.

Abstract: Methods and systems for a silicon-based optical phase modulator with high modal overlap are disclosed and may include, in an optical modulator having a rib waveguide in which a cross-shaped depletion region separates four alternately doped sections: receiving an optical signal at one end of the optical modulator, modulating the received optical signal by applying a modulating voltage, and communicating a modulated optical signal out of an opposite end of the modulator. The modulator may be in a silicon photonically-enabled integrated circuit which may be in a complementary-metal oxide semiconductor (CMOS) die. An optical mode may be centered on the cross-shaped depletion region. The four alternately doped sections may include: a shallow depth p-region, a shallow depth n-region, a deep p-region, and a deep n-region. The shallow depth p-region may be electrically coupled to the deep p-region periodically along the length of the modulator.

Abstract: Methods and systems for optical alignment to a silicon photonically-enabled integrated circuit may include aligning an optical assembly to a photonics die comprising a transceiver by, at least, communicating optical signals from the optical assembly into a plurality of grating couplers in the photonics die, communicating the one or more optical signals from the plurality of grating couplers to optical taps, with each tap having a first output coupled to the transceiver and a second output coupled to a corresponding output grating coupler, and monitoring an output optical signal communicated out of said photonic chip via said output grating couplers. The monitored output optical signal may be maximized by adjusting a position of the optical assembly. The optical assembly may include an optical source assembly comprising one or more lasers or the optical assembly may comprise a fiber array. Such a fiber array may include single mode optical fibers.

Abstract: Methods and systems for a free space CWDM MUX/DEMUX for integration with a grating coupler based silicon platform may include an optical assembly coupled to a photonic chip. The optical assembly includes a lens array on the top surface of the chip, an angled mirror, a plurality of transparent spacers, and a plurality of thin film filters. The optical assembly may receive an input optical signal comprising a plurality of optical signals at different wavelengths via an optical fiber coupled to the optical assembly, communicate the plurality of optical signals through a first of the plurality of transparent spacers, pass a first of the plurality of optical signals through a corresponding one of the plurality of thin film filters while reflecting others of the plurality of optical signals back into the first of the plurality of transparent spacers, and reflect the others of the plurality of signals towards a second of the plurality of thin film filters.

Abstract: Methods and systems for coupling a light source assembly to an optical integrated circuit are disclosed and may include a system comprising a laser source assembly having a laser, a rotator, and a mirror, where the laser source assembly is coupled to a die including an angled grating coupler and a waveguide. The system may generate an optical signal utilizing the laser, rotate the polarization of the optical signal utilizing the rotator, reflect the rotated optical signal onto the grating coupler on the die, and couple the optical signal to the waveguide, where an angle between a grating coupler axis that is parallel to the waveguide and a plane of incidence of the optical signal reflected to the angled grating coupler is non-zero. The angle between the grating coupler axis and the plane of incidence of the optical signal reflected to the angled grating coupler may be 45 degrees.

Abstract: A method and system is provided for cassette based wavelength division multiplexing and may include an optical system with an aggregating cassette. The optical system may include optical transceivers, with each generating optical signals at a different wavelength. The aggregating cassette may include one or more multiplexers coupled to each of the optical transceivers via optical fibers. The optical transceivers may generate modulated optical signals at one of the different wavelengths. The optical fibers may communicate one of the modulated optical signals from each of the optical transceivers to the one or more multiplexers. The modulated optical signals may be multiplexed to one or more output optical fibers. The multiplexed signals may be communicated to one or more receiving demultiplexers using the one or more output optical fibers. The one or more demultiplexers may demultiplex said multiplexed signals into separate wavelength signals.

Abstract: A system for a differential trans-impedance amplifier circuit comprising: an amplifier having a pair of input nodes and configured to generate an amplified replica of a differential voltage on said pair of input nodes; a photodiode; a pair of DC-blocking capacitors coupling said photodiode to said pair of input nodes; at least one resistance coupled between said pair of input nodes of said amplifier; and a bias network comprising two identical photodiode biasing resistances each photodiode biasing resistance coupled in series between said photodiode and a respective DC voltage. A feedback loop for the amplifier may include source followers that are operable to level shift voltages prior to coupling capacitors that couple said photodiode to said amplifier to ensure stable bias conditions for said amplifier. The source followers may include CMOS transistors. The amplifier may be integrated in a complementary metal-oxide semiconductor (CMOS) chip, which may include a CMOS photonics chip.

Abstract: Methods and systems for an optoelectronic built-in self-test (BIST) system for silicon photonics optical transceivers are disclosed and may include, in an optoelectronic transceiver having a transmit (Tx) path and a receive (Rx) path, where the Rx path includes a main Rx path and a BIST loopback path: generating a pseudo-random bit sequence (PRBS) signal, generating an optical signal in the Tx path by applying the PRBS signal to a modulator, communicating the optical signal to the BIST loopback path and converting to an electrical signal utilizing a photodetector, the photodetector being a replica of a photodetector in the main Rx path, and assessing the performance of the Tx and Rx paths by extracting a PRBS signal from the electrical signal. The transceiver may be a single complementary-metal oxide semiconductor (CMOS) die or in two CMOS die, where a first comprises electronic devices and a second comprises optical devices.

Abstract: Methods and systems for optoelectronics transceivers integrated on a CMOS chip are disclosed and may include receiving optical signals from optical fibers via grating couplers on a top surface of a CMOS chip, which may include a guard ring. Photodetectors may be integrated in the CMOS chip. A CW optical signal may be received from a laser source via optical couplers, and may be modulated using optical modulators, which may be Mach-Zehnder and/or ring modulators. Circuitry in the CMOS chip may drive the optical modulators. The modulated optical signal may be communicated out of the top surface of the CMOS chip into optical fibers via grating couplers. The received optical signals may be communicated between devices via waveguides. The photodetectors may include germanium waveguide photodiodes, avalanche photodiodes, and/or heterojunction diodes. The CW optical signal may be generated using an edge-emitting and/or a vertical-cavity surface emitting semiconductor laser.

Abstract: Methods and systems for stabilized directional couplers are disclosed and may include a system comprising first and second directional couplers formed by first and second waveguides, where one of the waveguides may comprise a length extender between the directional couplers. The directional couplers may be formed by reduced spacing between the waveguides on opposite sides of the length extender. An input optical signal may be communicated into one of the waveguides, where at least a portion of the input optical signal may be coupled between the waveguides in the first directional coupler and at least a portion of the coupled optical signal may be coupled between the waveguides in the second directional coupler. Optical signals may be communicated out of the system with magnitudes at a desired percentage of the input optical signal. The length extender may add phase delay for signals in one of the first and second waveguides.

Abstract: Methods and systems for a polarization immune wavelength division multiplexing demultiplexer are disclosed and may include, in an optoelectronic transceiver having an input coupler, a demultiplexer, and an amplitude scrambler: receiving input optical signals via the input coupler, communicating the input optical signals to the amplitude scrambler via waveguides, configuring the average optical power in each of the waveguides utilizing the amplitude scrambler, and demultiplexing the optical signals utilizing the demultiplexer. The amplitude scrambler may include phase modulators and a coupling section. The phase modulators may include sections of P-N junctions in the two waveguides. The demultiplexer may include a Mach-Zehnder Interferometer. The demultiplexed signals may be received utilizing photodetectors. The input coupler may include a polarization splitting grating coupler.

Abstract: 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 and modulate a second CW optical signal from the second light source utilizing the second modulator. 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.

Abstract: 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.

Abstract: Methods and systems for redundant light sources by utilizing two inputs of an integrated modulator are disclosed and may include: an optoelectronic transmitter integrated in a semiconductor die with first and second laser sources coupled to the semiconductor die, said optoelectronic transmitter comprising an optical modulator with a first input waveguide coupled to the first laser source and second input waveguide coupled to the second laser source, the optoelectronic receiver being operable to: configure the first laser source to provide an optical signal to the first input of the optical modulator; and if the first laser source does not provide an optical signal, configure the second laser source to provide an optical signal to the second input of the optical modulator. The first laser source may be optically coupled to the first input waveguide and the second laser source optically coupled to the second input waveguide using grating couplers.

Abstract: Methods and systems for encoding multi-level pulse amplitude modulated signals using integrated optoelectronics are disclosed and may include generating a multi-level, amplitude-modulated optical signal utilizing an optical modulator driven by first and second electrical input signals, where the optical modulator may configure levels in the multi-level amplitude modulated optical signal, drivers are coupled to the optical modulator; and the first and second electrical input signals may be synchronized before being communicated to the drivers. The optical modulator may include optical modulator elements coupled in series and configured into groups. The number of optical modular elements and groups may configure the number of levels in the multi-level amplitude modulated optical signal. Unit drivers may be coupled to each of the groups. The electrical input signals may be synchronized before communicating them to the unit drivers utilizing flip-flops.

Abstract: Methods and systems for a bi-directional receiver for standard single-mode fiber based on grating couplers may include, in an integrated circuit, a multi-wavelength grating coupler, and first and second optical sources coupled to the integrated circuit: coupling first and second source optical signals at first and second wavelengths into the photonically-enabled integrated circuit using the first and second optical sources, where the second wavelength is different from the first wavelength, receiving a first optical data signal at the first wavelength from an optical fiber coupled to the multi-wavelength grating coupler, and receiving a second optical data signal at the second wavelength from the optical fiber. Third and fourth optical data signals at the first and second wavelengths may be communicated out of the optoelectronic transceiver via the multi-wavelength grating coupler.

Abstract: A method and system for implementing high-speed electrical interfaces between semiconductor dies in optical communication systems are disclosed and may include communicating electrical signals between a first die and a second die via coupling pads which may be located in low impedance points in Tx and Rx paths. The electrical signals may be communicated via one or more current-mode, controlled impedance, and/or capacitively-coupled interfaces. The current-mode interface may include a cascode amplifier stage split between source and drain terminals of transistors on the dies. The controlled-impedance interfaces may include transmission line drivers on a first die and transmission lines on a second die. The capacitively-coupled interfaces may include capacitors formed by contact pads on the dies. The coupling pads may be connected via one or more of: wire bonds, metal pillars, solder balls, or conductive resin. The dies may comprise CMOS and may be coupled in a flip-chip configuration.

Abstract: Methods and systems for split voltage domain receiver circuits are disclosed and may include amplifying complementary received signals in a plurality of partial voltage domains. The signals may be combined into a single differential signal in a single voltage domain. Each of the partial voltage domains may be offset by a DC voltage from the other partial voltage domains. The sum of the partial domains may be equal to a supply voltage of the integrated circuit. The complementary signals may be received from a photodiode. The amplified received signals may be amplified via stacked common source amplifiers, common emitter amplifiers, or stacked inverters. The amplified received signals may be DC coupled prior to combining. The complementary received signals may be amplified and combined via cascode amplifiers. The voltage domains may be stacked, and may be controlled via feedback loops. The photodetector may be integrated in the integrated circuit.

Abstract: Methods and systems for monolithic integration of photonics and electronics in CMOS processes are disclosed and may include in an optoelectronic transceiver comprising photonic and electronic devices from two complementary metal-oxide semiconductor (CMOS) die with different silicon layer thicknesses for the photonic and electronic devices, the CMOS die bonded together by metal contacts: communicating optical signals and electronic signals to and from said optoelectronic transceiver utilizing a received continuous wave optical signal as a source signal. A first of the CMOS die includes the photonic devices and a second includes the electronic devices. Electrical signals may be communicated between electrical devices to the optical devices utilizing through-silicon vias coupled to the metal contacts. The metal contacts may include back-end metals from a CMOS process. The electronic and photonic devices may be fabricated on SOI wafers, with the SOI wafers being diced to form the CMOS die.