Abstract: Methods and systems for monolithic integration of photonics and electronics in CMOS processes are disclosed and may include fabricating photonic and electronic devices on two CMOS wafers with different silicon layer thicknesses for the photonic and electronic devices with at least a portion of each of the wafers bonded together, where a first of the CMOS wafers includes the photonic devices and a second of the CMOS wafers includes the electronic devices. The electrical devices may be coupled to optical devices utilizing through-silicon vias. The different thicknesses may be fabricated utilizing a selective area growth process. Cladding layers may be fabricated utilizing oxygen implants and/or utilizing CMOS trench oxide on the CMOS wafers. Silicon may be deposited on the CMOS trench oxide utilizing epitaxial lateral overgrowth. Cladding layers may be fabricated utilizing selective backside etching. Reflective surfaces may be fabricated by depositing metal on the selectively etched regions.

Abstract: Methods and systems for monolithic integration of photonics and electronics in CMOS processes are disclosed and may include fabricating photonic and electronic devices on two CMOS wafers with different silicon layer thicknesses for the photonic and electronic devices bonded to at least a portion of each of the wafers together, where a first of the CMOS wafers includes the photonic devices and a second of the CMOS wafers includes the electronic devices. The electrical devices may be coupled to optical devices utilizing through-silicon vias. The different thicknesses may be fabricated utilizing a selective area growth process. Cladding layers may be fabricated utilizing oxygen implants and/or utilizing CMOS trench oxide on the CMOS wafers. Silicon may be deposited on the CMOS trench oxide utilizing epitaxial lateral overgrowth. Cladding layers may be fabricated utilizing selective backside etching. Reflective surfaces may be fabricated by depositing metal on the selectively etched regions.

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 an electronics die and an optoelectronics 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: A method and system for bandwidth enhancement using hybrid inductors are disclosed and may include providing an electrical impedance that increases with frequency via hybrid inductors comprising a transistor, a capacitor, an inductor, and a resistor. A first terminal of the hybrid inductors may comprise a first terminal of the transistor. A second terminal of the transistor may be coupled to a first terminal of the resistor and a first terminal of the capacitor. A second terminal of the resistor may comprise a second terminal of the hybrid inductors. A third terminal of the transistor may be coupled to a first terminal of an inductor, and a second terminal of the inductor may be coupled to a second terminal of the capacitor. The hybrid inductors may be configured by varying transconductance, resistance, and/or capacitance and may be utilized as an amplifier load.

Abstract: Various embodiments described herein comprises an optoelectronic device comprising a waveguide structure including a plurality of optical modulator elements each having an optical property that is adjustable upon application of an electrical signal so as to modulate light guided in the waveguide structure. The optoelectronic device also comprises a plurality of amplifiers in distributed fashion. Each amplifier is electrically coupled to one of the optical modulators to apply electrical signals to the optical modulator.

Abstract: A method and system for optoelectronic receivers for uncoded data are disclosed and may include amplifying received electrical signals in a signal amplifier comprising differential gain stages with signal detectors coupled to the outputs. First and second output voltages may be tracked and held utilizing the signal detectors. A difference between the tracked and held value may be amplified in a feedback path of the gain stage, which enables the dynamic configuration of a decision level. The received electrical signals may be generated from an optical signal by a PIN detector, an avalanche photodiode, or a phototransistor. The electrical signal may be received from a read channel. The feedback path may comprise digital circuitry, including an A/D converter, a state machine, and a D/A converter. The detectors may comprise envelope detectors utilized to detect maximum or minimum voltages. The signal amplifier may be integrated in a photonically-enabled CMOS chip.

Abstract: Methods and systems for monolithic integration of photonics and electronics in CMOS processes are disclosed and may include fabricating photonic and electronic devices on a single CMOS wafer with different silicon layer thicknesses. The devices may be fabricated on a semiconductor-on-insulator (SOI) wafer utilizing a bulk CMOS process and/or on a SOI wafer utilizing a SOI CMOS process. The different thicknesses may be fabricated utilizing a double SOI process and/or a selective area growth process. Cladding layers may be fabricated utilizing one or more oxygen implants and/or utilizing CMOS trench oxide on the CMOS wafer. Silicon may be deposited on the CMOS trench oxide utilizing epitaxial lateral overgrowth. Cladding layers may be fabricated utilizing selective backside etching. Reflective surfaces may be fabricated by depositing metal on the selectively etched regions. Silicon dioxide or silicon germanium integrated in the CMOS wafer may be utilized as an etch stop layer.

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 two or more electrical input signals. 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. Phase addition may be synchronized utilizing one or more electrical delay lines. The optical modulator may be integrated on a single substrate, which may include one of: silicon, gallium arsenide, germanium, indium gallium arsenide, polymers, or indium phosphide.

Abstract: Various embodiments described herein comprises an optoelectronic device comprising a waveguide structure including a plurality of optical modulator elements each having an optical property that is adjustable upon application of an electrical signal so as to modulate light guided in the waveguide structure. The optoelectronic device also comprises a plurality of amplifiers in distributed fashion. Each amplifier is electrically coupled to one of the optical modulators to apply electrical signals to the optical modulator.

Abstract: Various embodiments described herein comprises an optoelectronic device comprising a waveguide structure including a plurality of optical modulator elements each having an optical property that is adjustable upon application of an electrical signal so as to modulate light guided in the waveguide structure. The optoelectronic device also comprises a plurality of amplifiers in distributed fashion. Each amplifier is electrically coupled to one of the optical modulators to apply electrical signals to the optical modulator.

Abstract: Methods and systems for split voltage domain transmitter circuits are disclosed and may include amplifying a received signal in a plurality of partial voltage domains. Each of the partial voltage domains may be offset by a DC voltage from the other partial voltage domains. A sum of the plurality of partial domains may be equal to a supply voltage of the integrated circuit. A series of diodes may be driven in differential mode via the amplified signals. An optical signal may be modulated via the diodes, which may be integrated in a Mach-Zehnder or a ring modulator. The amplified signals may be communicated to the diodes, connected in a distributed configuration, via even-mode coupled transmission lines. The partial voltage domains may be generated via stacked source follower or emitter follower circuits. The voltage domain boundary value may be at one half the supply voltage due to symmetric stacked circuits.

Abstract: High speed optical modulators can be made of k modulators connected in series disposed on one of a variety of semiconductor substrates. An electrical signal propagating in a microwave transmission line is tapped off of the transmission line at regular intervals and is amplified by k distributed amplifiers. Each of the outputs of the k distributed amplifiers is connected to a respective one of the k modulators. Distributed amplifier modulators can have much higher modulating speeds than a comparable lumped element modulator, due to the lower capacitance of each of the k modulators. Distributed amplifier modulators can have much higher modulating speeds than a comparable traveling wave modulator, due to the impedance matching provided by the distributed amplifiers.

Abstract: High speed optical modulators can be made of k modulators connected in series disposed on one of a variety of semiconductor substrates. An electrical signal propagating in a microwave transmission line is tapped off of the transmission line at regular intervals and is amplified by k distributed amplifiers. Each of the outputs of the k distributed amplifiers is connected to a respective one of the k modulators. Distributed amplifier modulators can have much higher modulating speeds than a comparable lumped element modulator, due to the lower capacitance of each of the k modulators. Distributed amplifier modulators can have much higher modulating speeds than a comparable traveling wave modulator, due to the impedance matching provided by the distributed amplifiers.

Abstract: Circuit topologies that provide extended bandwidth of operation are disclosed. The circuits have two stages that share inductors, in which in-phase current components sum at a summing node and flow together, increasing the magnitude of the current in the inductors. The inductive peaking exhibited by the circuits is increased without using excessively large inductors.

Abstract: Techniques are disclosed for providing modulation current that includes output impedance compensation with a feed-forward bandwidth enhancement and pre-distortion modulation to control waveform transition symmetry. A feedback circuit senses output node voltage and increases the overdrive voltage of a current source. This offsets the loss of current due to channel length modulation and increases the effective output impedance of the source. A feed-forward circuit enhances the bandwidth of the impedance compensation feedback loop. Waveform transition symmetry is improved by pre-distorting a laser modulation current by introducing an undershoot current on the falling edge of the modulating current.

Abstract: A circuit topology for high speed low voltage logic circuits is disclosed that reduces the number of levels of stacked active circuit elements from 3 to 2. Circuits providing a variety of logic functions are presented, including a latch, an exclusive OR gate, a combination XOR and latch, a multiplexer and a demultiplexer. Circuits built according to the principles of the invention have been operated at speeds of 40 GHz. The circuit topology can operate at supply voltages as low as 2V (for silicon or silicon-germanium based devices) and provide power saving of 25%–50% or more, depending on the logic function. In some embodiments, circuits comprising single ended or differential inputs can be provided.

Abstract: Techniques are disclosed for providing modulation current that includes output impedance compensation with a feed-forward bandwidth enhancement and pre-distortion modulation to control waveform transition symmetry. A feedback circuit senses output node voltage and increases the overdrive voltage of a current source. This offsets the loss of current due to channel length modulation and increases the effective output impedance of the source. A feed-forward circuit enhances the bandwidth of the impedance compensation feedback loop. Waveform transition symmetry is improved by pre-distorting a laser modulation current by introducing an undershoot current on the falling edge of the modulating current.

Abstract: Circuit topologies that provide extended bandwidth of operation are disclosed. The circuits have two stages that share inductors, in which in-phase current components sum at a summing node and flow together, increasing the magnitude of the current in the inductors. The inductive peaking exhibited by the circuits is increased without using excessively large inductors.

Abstract: A circuit topology for high speed low voltage logic circuits is disclosed that reduces the number of levels of stacked active circuit elements from 3 to 2. Circuits providing a variety of logic functions are presented, including a latch, an exclusive OR gate, a combination XOR and latch, a multiplexer and a demultiplexer. Circuits built according to the principles of the invention have been operated at speeds of 40 GHz. The circuit topology can operate at supply voltages as low as 2V (for silicon or silicon-germanium based devices) and provide power saving of 25%-50% or more, depending on the logic function. In some embodiments, circuits comprising single ended or differential inputs can be provided.