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: A transmitter modulates a first polarization signal at a wavelength with a first data signal using intensity modulation. The transmitter modulates a second polarization signal at the same wavelength with a second data signal using intensity modulation. The transmitter combines the modulated, polarization signals and generates an output signal. A receiver includes a photodetector that receives the output signal and generates an electrical output signal including components of both modulated, polarization signals. A signal processing circuit implements correlation techniques or matching filters to recover the first and second data signal from the electrical output signal.

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 directly modulated semiconductor laser whose optical output can be modulated by varying the transmittance of an end reflector of the laser cavity. In an example embodiment, the end reflector can be implemented using a lightwave circuit in which optical waveguides are arranged to form an optical interferometer. At least one of the optical waveguides may include a waveguide section configured to modulate the phase of an optical beam passing therethrough in response to an electrical radio-frequency drive signal in a manner that causes the transmittance and reflectance of the end reflector to be modulated accordingly. Advantageously, relatively high (e.g., >10 GHz) phase and/or amplitude modulation speeds of the optical output can be achieved in this manner to circumvent the inherent modulation-speed limitations of the laser's gain medium.

Abstract: An optical interconnect circuit for transmitting data between two or more electronic chips. In an example embodiment, the optical interconnect circuit comprises two or more photonic chips, each of which is vertically stacked with the corresponding electronic chip such that compact optical modulators and/or photodetectors of the photonic chip are in close proximity to the data sources/sinks of the corresponding electronic chip. Multi-core optical fibers and vertical coupling structures are used to provide multiple optical connections between different photonic chips. Advantageously, the provided capability to place optical modulators close to the data sources and to place photodetectors close to the data sinks can be used to reduce the amount of required electrical wiring. Optical-waveguide connections to the multi-core fibers can be used to allow for high density of optical conduits without spatially constraining the placement of data sources and/or data sinks on the electronic chips.

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: A directly modulated semiconductor laser whose optical output can be modulated by varying the transmittance of an end reflector of the laser cavity. In an example embodiment, the end reflector can be implemented using a lightwave circuit in which optical waveguides are arranged to form an optical interferometer. At least one of the optical waveguides may include a waveguide section configured to modulate the phase of an optical beam passing therethrough in response to an electrical radio-frequency drive signal in a manner that causes the transmittance and reflectance of the end reflector to be modulated accordingly. Advantageously, relatively high (e.g., >10 GHz) phase and/or amplitude modulation speeds of the optical output can be achieved in this manner to circumvent the inherent modulation-speed limitations of the laser's gain medium.

Abstract: A photonic integrated circuit (PIC) having two tapered planar waveguide cores that are separated from one another by a relatively narrow gap, with each of these waveguide cores having a respective portion thereof located on a tapered planar slab core. The relative positions of the slab core and the two waveguide cores are such that the light crossing between the two waveguide cores undergoes a polarization rotation between the TM and TE polarizations with a relatively low insertion loss. The corresponding waveguide structure can be used as a relative polarization-rotating splitter for light propagating in one direction or as a relative polarization-rotating combiner for light propagating in the opposite direction. At least some embodiments of the disclosed PIC can advantageously be fabricated using a complementary metal oxide semiconductor technology and/or a conventional silicon-on-insulator platform.

Abstract: A modular optical device having a set of optoelectronic modules that enables the device to operate, e.g., as a WDM or multichannel transceiver. In an example embodiment, the set of optoelectronic modules includes a laser module, a modulator module, and an optical-to-electrical converter module, all mounted on the same circuit board and optically and electrically connected for the intended application. Each of the optoelectronic modules comprises a respective stack of integrated circuits, at least one of which is a photonic integrated circuit (PIC). Some of the PICs may be configurable for different applications, with the configuration setup being carried out using electrical control signals and/or optical connections of the PICs.

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: A modular optical device having a set of optoelectronic modules that enables the device to operate, e.g., as a WDM or multichannel transceiver. In an example embodiment, the set of optoelectronic modules includes a laser module, a modulator module, and an optical-to-electrical converter module, all mounted on the same circuit board and optically and electrically connected for the intended application. Each of the optoelectronic modules comprises a respective stack of integrated circuits, at least one of which is a photonic integrated circuit (PIC). Some of the PICs may be configurable for different applications, with the configuration setup being carried out using electrical control signals and/or optical connections of the PICs.

Abstract: Various exemplary embodiments relate to an apparatus including: a first substrate including a planar dielectric layer on a semiconducting layer, and a silicon layer located directly on a planar surface of the dielectric layer, adjacent first and second segments of the silicon layer being optically end-coupled, the first segment being thicker than the second segment; and a second substrate including a III-V semiconductor layer segment on a top surface thereof, the first and second substrates being bonded together such that the III-V semiconductor layer segment is in direct contact with a portion of the first segment of the silicon layer.