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.

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 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: The locking of optical carriers to a grid can be achieved by employing an optical filter that exhibits athermal behavior in a frequency range to lock at least the frequency of a first channel to a target frequency. The locked frequency may be used to tune and lock the location of the free spectral range of a bandpass filter having transmission peaks at intervals, e.g., an FSR, corresponding to the target grid. The bandpass filter is used generate feedback signals that are used to lock the remaining frequencies to the grid. The athermal filter may be integrated on a silicon photonic integrated circuit.

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 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: The locking of optical carriers to a grid can be achieved by employing an optical filter that exhibits athermal behavior in a frequency range to lock at least the frequency of a first channel to a target frequency. The locked frequency may be used to tune and lock the location of the free spectral range of a bandpass filter having transmission peaks at intervals, e.g., an FSR, corresponding to the target grid. The bandpass filter is used generate feedback signals that are used to lock the remaining frequencies to the grid. The athermal filter may be integrated on a silicon photonic integrated circuit.

Abstract: An apparatus includes an optical data modulator, an electrical tuner located to control an operating wavelength of the optical data modulator, a photo-sensitive diode or photo-sensitive transistor, and an electronic feedback controller. The photo-sensitive diode or photo-sensitive transistor is connected to receive light from an optical output of the optical data modulator and is configured to output an electrical signal representative of a measured intensity of said received light. The electronic feedback controller is connected to receive the electrical signal from the optical intensity detector and to operate said electrical tuner based on an alternating current component of said measured intensity.

Abstract: An apparatus comprising a substrate having a silicon waveguide thereon. The apparatus also comprises a semiconductor layer with a direct band gap. The semiconductor layer is located on a segment of the silicon waveguide and the semiconductor layer and the silicon waveguide are in a hybrid optical waveguide.

Abstract: An apparatus comprising an optical filter located on a substrate. The optical filter including an optical splitter configured to receive an input light and an interferometer having two waveguide arms having different optical path-lengths from each other. The waveguide arms configured to receive the input light from the optical splitter. At least a portion of one of the two waveguide arms has a narrower core width than a wider core width of the other waveguide arm. The waveguide arm with the longest waveguide portion having the narrower core width has the longest total physical path-length of the two waveguide arms. At least one of the two waveguide arms having a set of discrete waveguide portions, the discrete waveguide portions of the set being connected by optical switches which are configured to tunably select from a plurality of different physical path-lengths through the discrete waveguide portions of the at least one waveguide arm.

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.

Abstract: An apparatus includes an optical transmitter configured to provide an optical signal amplitude-modulated among M different levels. A constellation control module is configured to provide a drive signal to control the optical signal. A feedback module is configured to receive a measure of spacing between amplitude peaks of a symbol constellation of the optical signal. The feedback module is further configured to regulate the constellation control module to adjust the optical signal in response to the measure of spacing.

Abstract: We disclose an optical transport system configured to transport data using a PDM-modulation format, in which each of two orthogonal polarizations is independently amplitude-modulated, and the relative phase between the carrier waves of the two polarizations may also be modulated. This modulation format enables the optical receiver to perform direct optical detection using a Stokes-vector detector to fully recover the encoded data.

Abstract: An apparatus includes a controllable optical interferometer having first and second external optical ports and a traveling-wave modulation electrode. The apparatus also includes an electrical driver configured and connected to apply a voltage with a periodic modulation to the traveling-wave modulation electrode such that the controllable optical interferometer operates as an optical isolator over a wavelength range.

Abstract: An apparatus according to an exemplary aspect of the present disclosure includes, among other things, a substrate, at least one semiconductor light-detector on the substrate and an optical waveguide on the substrate. The optical waveguide is configured to guide light to the at least one light-detector, one or more vias in a surface of the substrate or one or more ridges on the surface of the substrate. The one or more vias or ridges are configured to at least partially interrupt light propagating along the surface toward the at least one semiconductor light-detector from outside the optical waveguide.