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.

Abstract: A tunable optical apparatus comprises a silicon photonic integrated circuit region and a semiconductor optical amplifier optically coupled to each other. Tuning is achieved by having a first variable optical gate in off-state so as to substantially avoid attenuation of power of a first optical signal propagating through a first optical path and by having a second variable optical gate in on-state so as to attenuate power of a second optical signal propagating through a second optical path, the first optical path and the second optical path being optically coupled to the semiconductor optical amplifier.

Abstract: An apparatus comprising a wafer substrate having a planar optical layer thereon and a plurality of adjacent pairs of sacrificial optical testing parts and optical circuit parts located on the optical layer. The sacrificial testing part includes a vertical optical coupler that is oriented to redirect a test light signal between a direction substantially non-parallel to the planar optical layer and a direction that is substantially parallel to the planar optical layer. The optical circuit part includes an optical edge coupling port oriented to permit transfer of the test light signal through the optical edge coupling port and between the sacrificial testing part and the optical circuit part. The apparatus also comprises a trench located in the planar optical layer, the trench separating the sacrificial testing part from the optical circuit part for each of the plurality of adjacent pairs such that the test light signal passes across the trench between the sacrificial testing part and the optical circuit part.

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: A device includes a passive photonic layer located over a substrate and including at least one passive photonic element configured to propagate an optical signal therein. An electronic layer located between said substrate and said passive photonic layer includes at least one electronic device configured to propagate an electrical signal therein. An active photonic layer located over said passive photonic layer includes an active photonic device optically coupled to said passive photonic element and configured to convert between said electrical signal and said optical signal.

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 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.