Abstract: Aspects of the subject disclosure may include, for example, an optical modem that includes a tunable optical separator that separates optical signals into distinct wavelengths, resulting in a first optical signal with a first wavelength and a second optical signal with a second wavelength. A controller detects crosstalk between these signals due to operational variances in the tunable optical separator and performs adjustments to the tunable optical separator to reduce crosstalk. Other embodiments are disclosed.

Abstract: Aspects of the subject disclosure may include, for example, mixing a local oscillator (LO) signal produced by a LO source and an incoming optical signal to produce a beat signal having a beat signal power, monitoring the beat signal power, and responsive to the monitoring, adjusting an optical power of the LO signal to control the beat signal power. Other embodiments are disclosed.

Abstract: A method of operating a coherent transmitter in a time division multiple access (TDMA) system includes operating in an OFF state while the coherent transmitter is not assigned to transmit data in the TDMA system, wherein operating in the OFF state comprises generating a laser output having a dummy frequency different from an active frequency used to transmit data in the TDMA system; and operating in an ON state while the coherent transmitter is assigned to transmit data in the TDMA system, wherein operating in the ON state comprises generating an active laser output having the active frequency and modulating the active laser output using a modulator. Advantageously, the coherent transmitter can be used at an optical network unit (ONU) in a coherent passive optical network (CPON).

Abstract: Aspects of the subject disclosure may include, for example, mixing a local oscillator (LO) signal produced by a LO source and an incoming optical signal to produce a received optical signal directed to one or more photodetectors to produce a photocurrent that is supplied to an amplifier, monitoring the photocurrent supplied to the amplifier, and responsive to the monitoring, causing the LO source to perform an adjustment of an optical power of the LO signal to control the photocurrent supplied to the amplifier to avoid an overload condition. Other embodiments are disclosed.

Abstract: Aspects of the subject disclosure may include, for example, system, comprising a substrate having an interconnect in or on a surface of the substrate, a riser disposed over the surface, the riser being configured with one or more through riser vias for coupling to the interconnect, a device positioned over the surface, the device having one or more conductive contacts residing in a plane of the device, and one or more wire bonds coupling the one or more through riser vias with the one or more conductive contacts thereby enabling connectivity of the interconnect to be raised toward or to the plane of the device such that at least one of the one or more wire bonds has a limited physical length. Other embodiments are disclosed.

Abstract: Disclosed are differential-drive electro-optic modulator structures for linear electro-optic (Pockels) platforms such as thin-film LiNbO3 (TFLN), directly compatible with traditional differential-output analog drivers, such as a linear electro-optic modulator, including: a first signal trace; a second signal trace, wherein the first signal trace and the second signal trace are driven by a differential signal; a first optical arm; and a second optical arm, wherein a geometry of the first signal trace and the second signal trace causes the differential signal to modulate optical signals in the first optical arm and the second optical arm, such that when the optical signals are combined to create a resultant optical signal, the geometry mitigates chirp in the resultant optical signal. Other embodiments are disclosed.

Abstract: An avalanche photodiode includes a silicon layer on a substrate; a germanium layer on the silicon layer; and a plurality of contacts including a cathode, an anode, and at least two separate gain tuning contacts configured to adjust an electric field to tune multiplication of carriers. The at least two separate gain tuning contacts are configured to control the electric field in the germanium layer and silicon layer. The at least two separate gain tuning contacts are configured to tailor the electric field such that the multiplication of carriers is greater in the silicon layer than the germanium layer. This added gain tuning control can be used to tailor the electric field profile such that multiplication happens mostly in silicon to achieve lower excess noise and little to no bandwidth variation.

Abstract: Aspects of the subject disclosure may include, for example, a differential biasing device that includes first and second bias tees having respective high-frequency biased terminals, high-frequency unbiased terminals and biasing terminals. The first and second bias tees can be configured at least partially on and/or within different layers of a substrate to facilitate a compact configuration. The layers can include surface layers and/or internal layers that enable an overlapping of at least portions of the first and second bias tees. Other embodiments are disclosed.

Abstract: An optical modulator includes an optical waveguide extending a length and three Radio Frequency (RF) electrodes configured to modulate an optical signal in the waveguide. The RF electrodes include an RF crossing positioned at or near an end of the length and configured to equalize the optical signal by introducing destructive interference after the crossing. At this location, high-frequency components of the optical signal are already attenuated, while low-frequency components are selectively reduced, thereby flattening the electro-optic frequency response. The RF crossing may implement topologies including GSG-to-SGS transitions, stacked or staggered electrode arrangements, symmetrical or asymmetrical crossings, or multi-layer implementations. The geometry and placement of the RF crossing are selected to maintain impedance and velocity matching while optimizing equalization.

Abstract: Positioned between first and second planes of a volume are one or more optical elements. Light-impeding structures absorb light, reflect light, or both. Each light-impeding structure in a first set: intersects the first (and second) plane with a first (and second) cross-sectional shape, comprises a first (and second) maximum cross-sectional length equal to the length of the longest line between two maximally separated points of the first (and second) cross-sectional shape, and is separated from nearest neighboring light-impeding structures in the first set by a distance no larger than four times the length of the first maximum cross-sectional length or four times the length of the second maximum cross-sectional length. Light propagation through one or more points is impeded, such that any line that intersects at least one of the points, is entirely within the volume, and traverses through the first set, intersects at least one light-impeding structure.

Abstract: In-situ Polarization Extinction Ratio (PER) monitoring in a photonic device, such as a Silicon Photonics (SiP) chip, Photonic Integrated Circuit (PIC), and the like is disclosed. The photonic device includes a PIC; and a laser connected to an input of the PIC via Polarization-maintaining (PM) devices; wherein the PM device has a desired polarization axis on a first mode and undesired on a second undesired mode, and wherein the PIC includes an on-chip first monitoring photodiode and circuitry configured to determine Polarization Extinction Ratio (PER) based on an optical power measured by the on-chip first monitoring photodiode.

Abstract: Aspects of the subject disclosure may include, for example, a flexible printed circuit (FPC) for interconnecting an optical device and an application specific integrated circuit (ASIC), wherein the FPC includes a first section that is configured with a first plurality of electrically conductive traces and a second section over which one or more components are disposed, and wherein the second section is configured with a second plurality of electrically conductive traces that extend from the first plurality of electrically conductive traces to the one or more components. Other embodiments are disclosed.

Abstract: A first (second) electrical input port receives a first (second) drive signal. A first (second) transmission line is configured to propagate a first (second) electromagnetic wave over at least a portion of a first (second) optical waveguide arm of an MZI to apply an optical phase modulation. A drive signal interconnection structure is configured to provide a first electrical connection between the first electrical input port and an inner electrode shared by the transmission lines, and a second electrical connection between the second electrical input port and respective outer electrodes of the transmission lines; and is configured to preserve relative phase shifts between the drive signals. An impedance associated with a first electric field distribution between the inner electrode and a first of the outer electrodes is substantially equal to an impedance associated with a second electric field distribution between the inner electrode and a second of the outer electrodes.

Abstract: An optical modulator includes an optical waveguide extending a length; and a plurality of Radio Frequency (RF) electrodes configured to modulate an optical signal in the optical waveguide, wherein the RF electrodes include an RF crossing located an end of the length and that is configured to equalize the optical signal. The optical signal is equalized via destructive interference after the RF crossing for attenuating modulation amplitude. At or near the end of the length, high frequencies of the optical signal are already strongly attenuated whereas low frequencies of the optical signal are not such that the low frequencies are equalized after the RF crossing.

Abstract: A coherent optical modem is configured to support fast Loss of Signal (LOS) detection, e.g., <1 ms, and includes an Intradyne Coherent Receiver (ICR) with input power reporting circuitry configured to monitor one or more received optical signals; and processing circuitry communicatively coupled to the ICR and configured to receive a first interrupt from the input power reporting circuitry based on the input power reporting circuitry monitoring the one or more received optical signals, responsive to the first interrupt, prioritize detection of LOS in the processing circuitry, and, responsive to the detection of the LOS, provide a second interrupt to a host device associated with the coherent optical modem.

Abstract: Aspects of the subject disclosure may include, for example, a device, comprising an optical package, a frequency discriminator configured to provide complementing signals that include phase noise associated with a local oscillator (LO) input, a transimpedance amplifier (TIA) system adapted to provide one or more phase information signals by amplifying a difference of the complementing signals, and an application specific integrated circuit (ASIC) configured to process the one or more phase information signals to derive an estimation of the phase noise, wherein the frequency discriminator is implemented in the optical package and integrated with the TIA system and the ASIC to facilitate avoidance of enhanced equalized phase noise (EEPN). Other embodiments are disclosed.

Abstract: Positioned between first and second planes of a volume are one or more optical elements. Light-impeding structures absorb light, reflect light, or both. Each light-impeding structure in a first set: intersects the first (and second) plane with a first (and second) cross-sectional shape, comprises a first (and second) maximum cross-sectional length equal to the length of the longest line between two maximally separated points of the first (and second) cross-sectional shape, and is separated from nearest neighboring light-impeding structures in the first set by a distance no larger than four times the length of the first maximum cross-sectional length or four times the length of the second maximum cross-sectional length. Light propagation through one or more points is impeded, such that any line that intersects at least one of the points, is entirely within the volume, and traverses through the first set, intersects at least one light-impeding structure.

Abstract: Driving an optical modulator is described. A control circuit generates first and second target voltages based on a target phase modulation between first and second optical waveguide arms of the optical modulator. An offset control circuit generates first and second offset signals. A linear modulator driver receives the first and second target voltages and the first and second offset signals, and generates a first output voltage for biasing the first optical waveguide arm and a second output voltage for biasing the second optical waveguide arm. Feedback circuitry can feed the first and second output voltages to the offset control circuit, which can generate the first and second offset signals using the first and second output voltages. The output voltages bias the waveguide arms so the optical modulator operates close to the target phase modulation, even in the presence of manufacturing errors.

Abstract: Aspects of the subject disclosure may include, for example, a flexible printed circuit (FPC) for interconnecting an optical device and an application specific integrated circuit (ASIC), wherein the FPC includes a first section that is configured with a first plurality of electrically conductive traces and a second section over which one or more components are disposed, and wherein the second section is configured with a second plurality of electrically conductive traces that extend from the first plurality of electrically conductive traces to the one or more components. Other embodiments are disclosed.

Abstract: Driving an optical modulator is described. A control circuit generates first and second target voltages based on a target phase modulation between first and second optical waveguide arms of the optical modulator. An offset control circuit generates first and second offset signals. A linear modulator driver receives the first and second target voltages and the first and second offset signals, and generates a first output voltage for biasing the first optical waveguide arm and a second output voltage for biasing the second optical waveguide arm. Feedback circuitry can feed the first and second output voltages to the offset control circuit, which can generate the first and second offset signals using the first and second output voltages. The output voltages bias the waveguide arms so the optical modulator operates close to the target phase modulation, even in the presence of manufacturing errors.