Abstract: An apparatus including an optical modulator and an electronic controller. The optical modulator includes a parallel-nested pair of MZIs, each arm of the MZIs including one or more EAMs therein. The electronic controller is electrically connected to drive the MZIs such that the optical modulator outputs an optical carrier modulated according to a quadrature amplitude modulation constellation with at least five different symbols.

Abstract: An optoelectronic circuit used with signal light comprises photonic devices disposed on a platform. The photonic devices are configured to condition the signal light and are fabricated with an optical characteristic being electronically tunable. A fabricated performance of the optical characteristic can be varied from a target performance due to a difference (e.g., alteration, change, error, or discrepancy) in the process used to fabricate the device. A ground bus, a power bus, and banks of electronic components are disposed on the platform in electrical communication with the photonic devices. The electronic components in a given bank are selectively configurable to tune the optical characteristic of the associated device so a variance can be diminished between the fabrication and target performances of the device's optical characteristic due to the difference in the fabrication process.

Abstract: An optical circuit is used with continuous wave signals having different wavelengths at a channel spacing from one another. A portion of the optical circuit is implemented in a photonic integrated circuit. Modulators in a modulation stage modulate the continuous wave signals to produce modulated signals. A multiplexing stage, which can have multiplexing filters, power combiners, or power couplers, multiplexes the continuous wave or modulated signals to produce multiplexed signals. The multiplexing stage may be placed either before or after the modulation stage. One or more polarization rotator and combiner (PRC) devices in a final stage combines the multiplexed signals into an output signal. The output signal has a first set of the different wavelengths at a first polarization and has a second separate set of the different wavelengths at a second polarization orthogonal to the first polarization.

Abstract: A photonic integrated circuit (PIC) device has photonic devices arranged in an array with respect to control and common conductors. Each of the photonic devices has a photonic component (e.g., photodiode, thermo-optic phase shifter, etc.) and a switching diode connected in series with one another between a control connection and a common connection. The photonic component has at least one optical port, which can be coupled to a waveguide in the PIC device. The switching diode is configured to switch between reverse and forward bias in response to the electrical signals. In this way, control circuitry for providing control and monitoring signals to the conductors can be greatly simplified, and the PIC device can be more compact.

Abstract: An apparatus including a carrier mount having a staircase of steps in an opening in the carrier mount and a plurality of dies, each one of the dies having at least a portion of an edge of a major surface thereof located on one of the steps corresponding to the one of the dies such that the dies form a stack, major surfaces of the dies being substantially parallel in the stack, each of the dies having one or more electro-optical devices thereon.

Abstract: An apparatus including a carrier mount having a staircase of steps in an opening in the carrier mount and a plurality of dies, each one of the dies having at least a portion of an edge of a major surface thereof located on one of the steps corresponding to the one of the dies such that the dies form a stack, major surfaces of the dies being substantially parallel in the stack, each of the dies having one or more electro-optical devices thereon.

Abstract: An optical system having a plurality of ring resonators that can be tuned by regulating their local temperatures in a manner that enables: initial spectral alignment of the optical resonances with the desired carrier wavelengths; fine-tuning of the ring resonators to spectrally align a selected feature of the optical resonances with the carrier wavelengths; and continuous tuning of the ring resonators to counter any detuning thereof during operation. The initial spectral alignment can be performed using intensity/frequency modulation of different carrier wavelengths with different respective frequencies and detection of said frequencies in the photocurrents generated by the individual ring resonators under reverse-bias conditions.

Abstract: An optical device that can be used as an optical hybrid, e.g., in CMOS-compatible PICs. In an example embodiment, the optical device has a single optical input and four optical outputs. The two optical input signals to be mixed in the optical device are applied to the single optical input as transverse electric (TE) and transverse magnetic (TM) polarization components, respectively, of the corresponding polarization-multiplexed optical input signal. In response to the latter, the optical device causes the four outputs to receive four different relative-phase combinations of the two optical input signals, each combination being coupled into a TE waveguide mode at the respective optical output. A PIC having one or more instances of the optical device can be used, e.g., to implement a coherent optical receiver, wherein the TE and TM polarization components of the optical input signal are populated by a communication signal and a local-oscillator signal.

Abstract: An apparatus including an optical modulator and an electronic controller. The optical modulator includes a parallel-nested pair of MZIs, each arm of the MZIs including one or more EAMs therein. The electronic controller is electrically connected to drive the MZIs such that the optical modulator outputs an optical carrier modulated according to a quadrature amplitude modulation constellation with at least five different symbols.

Abstract: An apparatus including an external cavity laser with an optical cavity, the optical cavity bounded by optical reflectors. The optical cavity can include an optical gain module capable of amplifying light, a tunable endless optical phase shifter and a wavelength-tunable optical filter. The apparatus can also include an electronic control module connected to enable adjustment of a phase shift accumulated by the light propagating through the tunable endless optical phase shifter and connected to enable adjustment of a passband wavelength of the wavelength tunable optical filter. Another apparatus as described above with no wavelength-tunable optical filter present.

Abstract: An apparatus including first, second, third and fourth photodiodes, optical mixer and first and second optical power splitters. The optical mixer has two or more input ports, three output ports to output first, second and third mixtures of light corresponding to input light received from the input ports and transferred to the output ports. The first splitter has an input port and first and second output ports, to transmit part of one of the mixtures of light from one of the output ports to the first photodiode and a remaining part of the one mixture of light from the other one of the output ports to the third photodiode. The second splitter has an input port and first and second output ports, the second splitter to transmit part of another one of the mixtures of light from one of the output ports to the first photodiode and a remaining part of the other one of the mixtures of light from the other one of the output ports to the fourth photodiode.

Abstract: A photonic chip having a photonic-circuit layer supported on a substrate, the photonic-circuit layer including a suspended portion that extends beyond the outline of the substrate on the photonic-circuit layer. In various embodiments, the suspended portion may host one or more functional optical elements, such as an on-chip grating coupler, an on-chip microring resonator, and an on chip optical waveguide, that can be used to couple light in and out of the photonic chip. The geometry of the suspended portion enables unencumbered (e.g., double-sided) access to the one or more functional optical elements located therein and can advantageously be used to place an optical fiber and/or a second photonic chip sufficiently close to those functional optical elements to achieve a high chip-to-fiber or chip-to-chip optical-coupling efficiency.

Abstract: An optical system having a plurality of ring resonators that can be tuned by regulating their local temperatures in a manner that enables: initial spectral alignment of the optical resonances with the desired carrier wavelengths; fine-tuning of the ring resonators to spectrally align a selected feature of the optical resonances with the carrier wavelengths; and continuous tuning of the ring resonators to counter any detuning thereof during operation. The initial spectral alignment can be performed using intensity/frequency modulation of different carrier wavelengths with different respective frequencies and detection of said frequencies in the photocurrents generated by the individual ring resonators under reverse-bias conditions.

Abstract: A photonic chip having a photonic-circuit layer supported on a substrate, the photonic-circuit layer including a suspended portion that extends beyond the outline of the substrate on the photonic-circuit layer. In various embodiments, the suspended portion may host one or more functional optical elements, such as an on-chip grating coupler, an on-chip microring resonator, and an on chip optical waveguide, that can be used to couple light in and out of the photonic chip. The geometry of the suspended portion enables unencumbered (e.g., double-sided) access to the one or more functional optical elements located therein and can advantageously be used to place an optical fiber and/or a second photonic chip sufficiently close to those functional optical elements to achieve a high chip-to-fiber or chip-to-chip optical-coupling efficiency.

Abstract: An apparatus includes a planar structure having a top surface, a bottom surface, and an edge; and an optical grating located near or at the top surface and having a regular pattern of features. The planar structure has a cavity, and a portion of the cavity is located between opposing portions of the top and bottom surfaces. The optical grating is adjacent to the edge and is over, at least a part of the cavity. The apparatus includes an optically reflective coating on a portion of a wall of the cavity below the optical grating. The cavity has an opening along a portion of the edge of the planar structure.

Abstract: An apparatus includes a substrate having a planar surface and an optical waveguide having an optical core located on said substrate. The optical core is along and may even be parallel to said surface. A cross section of the optical core varies throughout a segment of the optical core. A light guiding direction of the optical waveguide bends through, at least, 90 degrees along the segment.

Abstract: An electro-optical circuit in which diode-like electrical characteristics of an optical modulator employed therein are used to generate one or more DC-offset levels that place the optical modulator into a proper electrical operating configuration for modulating light transmitted therethrough. In an example embodiment, the optical modulator includes an optical waveguide comprising at least a portion of a semiconductor diode connected to a data driver using a clamping circuit, the clamping circuit being configured to cause a data-modulated electrical signal outputted by the data driver to set a DC-offset level applied to the semiconductor diode. As a result, the use of on-chip and/or on-board bias-tees can advantageously be avoided. In some embodiments, the optical modulator can be driven using two different data signals, each used to set a different respective DC-offset level at the semiconductor diode. In various embodiments, the optical modulator can be an intensity modulator and/or a phase modulator.

Abstract: An optical apparatus comprising an optical device having an optical input-output face, at least two planar waveguide arms being located on a substrate, an optical splitter being located on the substrate, and, an optical grating coupler being located on the substrate. The optical splitter has an optical input and a plurality of optical outputs, each optical output being optically connected to a corresponding one of the planar waveguide arms. The optical grating coupler is connected to receive light from each planar waveguide arm and form diffraction pattern therefrom such that a principal maximum of one of the diffraction patterns overlaps with a principal maximum of another of the diffraction patterns on the optical input-output face of the optical device, the principal maxima of the one and another of the diffraction patterns being directed in different directions.

Abstract: An optical device that can be used as an optical hybrid, e.g., in CMOS-compatible PICs. In an example embodiment, the optical device has a single optical input and four optical outputs. The two optical input signals to be mixed in the optical device are applied to the single optical input as transverse electric (TE) and transverse magnetic (TM) polarization components, respectively, of the corresponding polarization-multiplexed optical input signal. In response to the latter, the optical device causes the four outputs to receive four different relative-phase combinations of the two optical input signals, each combination being coupled into a TE waveguide mode at the respective optical output. A PIC having one or more instances of the optical device can be used, e.g., to implement a coherent optical receiver, wherein the TE and TM polarization components of the optical input signal are populated by a communication signal and a local-oscillator signal.

Abstract: An optical apparatus comprising an optical device having an optical input-output face, at least two planar waveguide arms being located on a substrate, an optical splitter being located on the substrate, and, an optical grating coupler being located on the substrate. The optical splitter has an optical input and a plurality of optical outputs, each optical output being optically connected to a corresponding one of the planar waveguide arms. The optical grating coupler is connected to receive light from each planar waveguide arm and form diffraction pattern therefrom such that a principal maximum of one of the diffraction patterns overlaps with a principal maximum of another of the diffraction patterns on the optical input-output face of the optical device, the principal maxima of the one and another of the diffraction patterns being directed in different directions.