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 a first Radio Frequency (RF) line and a second RF line; an optical waveguide along a length of the modulator with an input and an output; and a plurality of segments along the length including a first set of segments, a single RF line crossing, and a second set of segments, wherein the first set of segments and the second set of segments have an inversion of their respective orientation at the RF line crossing, and wherein the RF line crossing is located off center relative to the plurality of segments, wherein each of the first RF line and the second RF line extend along the length and cross one another at the RF line crossing.

Abstract: A first transmission line comprises a first pair of electrodes receiving an electrical drive comprising first and second drive signals, which are loaded by a first series of p-n junctions applying optical phase modulation to respective optical waves propagating over a first section of the first and second optical waveguide arms of an MZI. A second transmission line comprises a second pair of electrodes configured to receive the electrical drive after an electrical signal delay. The second pair of electrodes are loaded by a second series of p-n junctions applying optical phase modulation to the respective optical waves propagating over a second section of the first and second optical waveguide arms after propagation over the first section. An electrode extension structure provides the electrical drive to the second pair of electrodes, and comprises an unloaded transmission line portion imposing the electrical signal delay based on an optical signal delay.

Abstract: Driving an optical modulator is described. A control circuit generates first and second input 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 offset signals, generates a first output voltage for biasing the first optical waveguide arm using the first offset signal, and generates a second output voltage for biasing the second optical waveguide arm using the second offset signal. 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: An optical modulator includes a first Radio Frequency (RF) line and a second RF line; an optical waveguide along a length of the modulator with an input and an output; and a plurality of segments along the length including a first set of segments, a single RF line crossing, and a second set of segments, wherein the first set of segments and the second set of segments have an inversion of their respective orientation at the RF line crossing, and wherein the RF line crossing is located off center relative to the plurality of segments, wherein each of the first RF line and the second RF line extend along the length and cross one another at the RF line crossing.

Abstract: A first transmission line comprises a first pair of electrodes receiving an electrical drive comprising first and second drive signals, which are loaded by a first series of p-n junctions applying optical phase modulation to respective optical waves propagating over a first section of the first and second optical waveguide arms of an MZI. A second transmission line comprises a second pair of electrodes configured to receive the electrical drive after an electrical signal delay. The second pair of electrodes are loaded by a second series of p-n junctions applying optical phase modulation to the respective optical waves propagating over a second section of the first and second optical waveguide arms after propagation over the first section. An electrode extension structure provides the electrical drive to the second pair of electrodes, and comprises an unloaded transmission line portion imposing the electrical signal delay based on an optical signal delay.

Abstract: An optical waveguide structure forms an MZI in proximity to an electro-optic material. A first (second) electrical input port is configured to receive a first (second) drive signal. The second drive signal has a negative amplitude relative to the first 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 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 electrode shared by the transmission lines, and a second electrical connection between the second electrical input port and respective electrodes of the transmission lines; and is configured to preserve relative phase shifts between the drive signals. Input impedances at the first and second electrical input ports are substantially equal to each other.

Abstract: An avalanche photodiode includes a silicon layer on a substrate; a germanium layer on the silicon layer; a cathode and an anode on any of the silicon layer and the germanium layer; and a plurality of contacts on the germanium layer, in addition to the cathode and the anode. The silicon layer can include a highly doped region at each end, an intrinsic doped region in a middle, and an intermediately doped region between the highly doped region at each end and the intrinsic doped region, and the cathode and the anode are each at a respective a highly doped region at each end. The germanium layer can include a plurality of highly doped regions with each including one of the plurality of contacts.

Abstract: An optical modulator includes multiple segments including modulator segments and a Radio Frequency (RF) crossing segment where RF lines extending a length of the modulator cross one another. The present disclosure includes optimization of one or more of a geometry of the RF crossing and a location of the RF crossing segment along the length. The geometry is selected so that the RF crossing segment appears as another segment having similar characteristics as modulator segments. The location of the RF crossing segment is selected to balance out fabrication error and phase efficiency.

Abstract: System and methods implemented in a coherent receiver having a pair of Avalanche Photodiodes (APD) include adjusting one or more of a reverse bias voltage (VAPD) on a P-path (VAPDP) and on an N-path (VAPDN) responsive to an output (PIN,CM) that indicates electrical power of an AC common-mode input signal; adjusting a Transimpedance Amplifier (TIA) common-mode AC response, AdjCM_AC_Response, responsive to an output (POUT,CM) that indicates electrical power of an AC common-mode output signal; and/or adjusting one or more of VAPDP and VAPDN responsive to received signal Signal-to-Noise Ratio (SNR).

Abstract: A first photodiode is integrated within at least a first layer of one or more semiconductor layers, the first photodiode comprising an active area optically coupled to a guided mode of a first waveguide to couple the first photodiode to an optical distribution network. One or more associated photodiodes are associated with the first photodiode integrated within at least the first layer in proximity to the first photodiode. An active area of a single associated photodiode or a sum of active areas of multiple associated photodiodes is substantially equal to the active area of the first photodiode. None of the associated photodiodes is coupled to the optical distribution network. Electrical circuitry is configured to generate a signal that represents a difference between (1) a signal derived from the first photodiode and (2) a signal derived from a single associated photodiode or a sum of signals derived from multiple associated photodiodes.

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: Driving an optical modulator is described. A control circuit generates first and second input 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 offset signals, generates a first output voltage for biasing the first optical waveguide arm using the first offset signal, and generates a second output voltage for biasing the second optical waveguide arm using the second offset signal. 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: An optical modulator device and method, including and utilizing: a first optical waveguide arm including one or more optical phase shifters, e.g., pn junctions, and configured to receive a first bias voltage Vbias1; and a second optical waveguide arm including one or more optical phase shifters, e.g., pn junctions, and configured to receive a second bias voltage Vbias2; wherein the first bias voltage Vbias1 and the second bias voltage Vbias2 are dissimilar, such that the first optical waveguide arm and the second optical waveguide arm exhibit a same phase modulation. Vbias1 and Vbias2 are selected such that the corresponding slopes V? of the associated phase shift versus applied bias voltage curves are equal. The optical modulator device further includes a driver coupled to the first optical waveguide arm and the second optical waveguide arm and including a current offset control circuit operable for providing Vbias1 and Vbias2.

Abstract: A coherent optical modem includes one or more inputs; one or more amplifier circuits, each coupled to a respective input of the one or more inputs; and one or more receiver circuits each including an analog-to-digital converter, each coupled to a respective amplifier circuit of the one or more amplifier circuits; wherein the one or more amplifier circuits are configured to implement an automatic gain control loop to provide a constant signal amplitude at an input of the analog-to-digital converter of a respective receiver circuit.

Abstract: An optical modulator includes multiple segments including modulator segments and a Radio Frequency (RF) crossing segment where RF lines extending a length of the modulator cross one another. The present disclosure includes optimization of one or more of a geometry of the RF crossing and a location of the RF crossing segment along the length. The geometry is selected so that the RF crossing segment appears as another segment having similar characteristics as modulator segments. The location of the RF crossing segment is selected to balance out fabrication error and phase efficiency.

Abstract: A photodetector circuit is disclosed. The photodetector circuit includes an optical input configured to receive a source optical signal for detection by the photodetector circuit, an optical waveguide for coupling the optical input and at least one side of a plurality of sides of a photodiode, wherein the optical waveguide is configured to generate a first optical signal and a second optical signal from the source optical signal, and the photodiode coupled to the first optical waveguide, where the photodiode is illuminated on the at least one side by the first and second optical signals at different locations on the photodiode, where the photodiode generates a photocurrent based on the first and second optical signals reducing photocurrent saturation. Providing a delay between the first and second optical signals reduces an out-of-band frequency response of the photodiode circuit.

Abstract: A flip-chip manufacture is described. Methods of blocking adhesive underfill in flip-chip high speed component manufacture include creating topology discontinuities to prevent adhesive underfill material from interacting with RF sensitive regions on substrates.

Abstract: A coherent optical modem includes one or more inputs; one or more amplifier circuits, each coupled to a respective input of the one or more inputs; and one or more receiver circuits each including an analog-to-digital converter, each coupled to a respective amplifier circuit of the one or more amplifier circuits; wherein the one or more amplifier circuits are configured to implement an automatic gain control loop to provide a constant signal amplitude at an input of the analog-to-digital converter of a respective receiver circuit.

Abstract: An amplifier circuit includes: an amplifier configured to receive at least one input signal and generate an output voltage in response to the at least one input signal and a gain control voltage; a voltage detector configured to generate a detector voltage based on the output voltage; a gain control summation circuit configured to generate an error signal by subtracting the detector voltage from a reference voltage; a loop filter configured to generate the gain control voltage based on the error signal and adjust the loop bandwidth in response to a loop filter adjust signal; and an analog automatic gain control bandwidth controller configured to monitor the detector voltage and the gain control voltage, to provide the reference voltage and the loop filter adjust signal, and to control a loop bandwidth of the output signal.