Abstract: An optical device with high thermal tuning efficiency is described. This optical device may be implemented using a tri-layer structure (silicon-on-insulator technology), including: a substrate, a buried-oxide layer and a semiconductor layer. In particular, a thermally tunable optical waveguide may be defined in the semiconductor layer. Furthermore, a portion of the substrate under the buried-oxide layer and substantially beneath a location of the thermally tunable optical waveguide is fabricated so that a portion of the buried-oxide layer is exposed. In this way, the thermal impedance between the thermally tunable optical waveguide and an external environment is increased, and power consumption associated with thermal tuning of the optical waveguide is reduced.

Abstract: An optical multiplexer/de-multiplexer (MUX/de-MUX) includes a two-dimensional pattern of features in a propagation region that conveys an optical signal having wavelengths. A given feature in this pattern has a characteristic length and the features have an average pitch, both of which are less than fundamental smallest of the wavelengths divided by an effective index of refraction of the propagation region. Moreover, an optical device in the optical MUX/de-MUX images and diffracts the optical signal using a reflective geometry, and provides the imaged and diffracted optical signal to output ports. For example, the optical device may include an echelle grating.

Abstract: A chip package includes an optical integrated circuit (such as a hybrid integrated circuit) and an integrated circuit that are proximate to each other in the chip package. The integrated circuit includes electrical circuits, such as memory or a processor, and the optical integrated circuit communicates optical signals with very high bandwidth. Moreover, a front surface of the integrated circuit is electrically coupled to a top surface of an interposer, and this top surface is in turn electrically coupled to a front surface of an input/output (I/O) integrated circuit that faces the top surface. Furthermore, the front surface of the I/O integrated circuit is electrically coupled to a top surface of the optical integrated circuit, where the top surface of the optical integrated circuit faces the front surface of the I/O integrated circuit.

Abstract: A chip package includes an optical integrated circuit (such as a hybrid integrated circuit) and an integrated circuit that are adjacent to each in the chip package. The integrated circuit includes electrical circuits, such as memory or a processor, and the optical integrated circuit communicates optical signals with very high bandwidth. Moreover, a front surface of the integrated circuit is electrically coupled to a front surface of the optical integrated circuit by a top surface of the interposer, where the top surface faces the front surface of the integrated circuit and the front surface of the optical integrated circuit. Furthermore, the integrated circuit and the optical integrated circuit may be on a same side of the interposer. By integrating the optical integrated circuit and the integrated circuit in close proximity, the chip package may facilitate improved performance compared to chip packages with electrical interconnects.

Abstract: An optical de-multiplexer (de-MUX) that includes an optical device that images and diffracts an optical signal using a reflective geometry is described, where a free spectral range (FSR) of the optical device associated with a given diffraction order abuts FSRs associated with adjacent diffraction orders. Moreover, the channel spacings within diffraction orders and between adjacent diffraction orders are equal to the predefined channel spacing associated with the optical signal. As a consequence, the optical device has a comb-filter output spectrum, which reduces a tuning energy of the optical device by eliminating spectral gaps between diffraction orders of the optical device.

Abstract: An interconnect module for communicating electrical signals and optical signals is described. In particular, an integrated circuit in the interconnect module receives and transmits the electrical signals with other components in a system that includes the interconnect module via an electrical connector. In addition, the integrated circuit receives and transmits electrical signals to a hybrid silicon-photonic bridge chip that performs electrical-to-optical and optical-to-electrical conversion. In turn, this bridge chip receives and transmits optical signals via an optical fiber. The interconnect module can be remateably connected to a backplane in the system, and can be arranged in a stacked configuration with other instances of the interconnect module. In these ways, the interconnect module facilitates dense, modular or scalable, and compact electrical and optical communication in the system.

Abstract: An integrated optical device includes a photo-detector (such as germanium) optically coupled to an optical waveguide. This photo-detector is deposited on the optical waveguide, and an optical signal propagating in the optical waveguide may be evanescently coupled to the photo-detector. In order to increase the absorption length of the photo-detector, a mirror (such as a distributed Bragg reflection grating) is included in the optical waveguide near the end of the photo-detector. This mirror reflects the optical signal back toward the photo-detector, thereby increasing the absorption of the optical signal by the photo-detector. In addition, absorption may be reduced by using electrical contacts that are electrically coupled to the photo-detector at locations where the optical mode of the optical signal is largely in the underlying optical waveguide, and by using a fingered metal layer to couple to the electrical contacts.

Abstract: A method for arbitration in an arbitration domain. The method includes: receiving, by each node of a plurality of nodes in the arbitration domain, an arbitration request from each sending node of the plurality of nodes in the arbitration domain, where the plurality of nodes in the arbitration domain each use a shared data channel to send data to a set of receiving nodes; assigning, by each node in the arbitration domain, consecutive time slots to each sending node based on a plurality of priorities assigned to the plurality of nodes in the arbitration domain; for each time slot: sending, from the arbitration domain, a switch request to a receiving node designated by the sending node, where the receiving node is in the set of receiving nodes; and sending, by the sending node, data to the receiving node via the shared data channel during the time slot.

Abstract: An integrated circuit includes an optical source that provides an optical signal to an optical waveguide. In particular, the optical source may be implemented by fusion-bonding a III-V semiconductor to a semiconductor layer in the integrated circuit. In conjunction with surrounding mirrors (at least one of which is other than a distributed Bragg reflector), this structure may provide a cavity with suitable optical gain at a wavelength in the optical signal along a vertical direction that is perpendicular to a plane of the semiconductor layer. For example, the optical source may include a vertical-cavity surface-emitting laser (VCSEL). Moreover, the optical waveguide, defined in the semiconductor layer, may be separated from the optical source by a horizontal gap in the plane of the semiconductor layer. During operation of the optical source, the optical signal may be optically coupled across the gap from the optical source to the optical waveguide.

Abstract: A multi-chip module (MCM) includes a stack of chips that are coupled using optical interconnects. On a first surface of a middle chip in the stack, there are: a first optical coupler, an optical waveguide, which is coupled to the first optical coupler, and a second optical coupler, which is coupled to the optical waveguide. The first optical coupler redirects an optical signal from the optical waveguide to a first direction (which is not in the plane of the first surface), or from the first direction to the optical waveguide. The second optical coupler redirects the optical signal from the optical waveguide to a second direction (which is not in the plane of the first surface), or from the second direction to the optical waveguide. An optical path associated with the second direction passes through an opening in a substrate in the middle chip.

Abstract: An optical device that includes multiple optical modulators having target operating wavelengths that are distributed over a band of wavelengths and actual operating wavelengths is described. For example, the target operating wavelengths of adjacent optical modulators may be separated by a wavelength increment. Moreover, because of differences between the actual operating wavelengths and the target operating wavelengths of the optical modulators, tuning elements may be used to tune the optical modulators so that the actual operating wavelengths match corresponding carrier wavelengths in a set of optical signals. Furthermore, control logic in the optical device may assign the optical modulators to the corresponding carrier wavelengths based at least on differences between the carrier wavelengths and the actual operating wavelengths, thereby reducing an average tuning energy associated with the tuning elements.

Abstract: An integrated optical component outputs and receives an optical signal that provides a comb of modulated wavelengths for use in wavelength-division-multiplexing (WDM) optical interconnects or links. In particular, a shared echelle grating is used as a wavelength-selective filter or control device for multiple lasing cavities to achieve self-registered and accurate lasing-channel spacing without inter-channel gain competition for multiplexing modulated wavelength channels into one transmit port, and for receiving and de-multiplexing WDM wavelength channels simultaneously. The wavelength alignment between a pair of such transceivers can be achieved by tuning the echelle grating on one side using thermal-optical or electro-optical effects. Furthermore, tunable ring-resonator modulators, broadband electro-absorption modulators (EAMs) or Mach-Zehnder Interferometer (MZI) optical modulators on the shared output waveguide outside of the lasing cavities can be used to modulate the wavelengths.

Abstract: An integrated optical source is described. This optical source outputs one or more optical signals that provide a comb of wavelengths for use in wavelength-division-multiplexing (WDM) optical interconnects or links. In particular, a shared echelle grating is used as a wavelength-selective filter or control device for multiple lasing cavities to achieve self-registered and accurate lasing-channel spacing without inter-channel gain competition. Furthermore, the optical source can be used to provide all the wavelength channels in one optical waveguide or in separate optical waveguides. Therefore, the optical source may be used with cascaded ring-resonator modulators and/or electro-absorption-based broadband modulators.

Abstract: An optical module is described. This optical module includes at least two optical devices that communicate with each other using edge-to-edge optical coupling of an optical signal between optical components in the two optical devices. Note that the edge-to-edge optical coupling may occur without mode converters at edges of either of the optical devices. Furthermore, the edge-to-edge optical coupling may be facilitated by an alignment substrate, which is mechanically coupled to the two optical devices. This alignment substrate aligns the edges of the two optical devices so that they are approximately parallel to each other, and aligns the optical components in the two optical devices.

Abstract: An optical source uses feedback to maintain a substantially fixed spacing between adjacent wavelengths in a set of wavelengths in a wavelength comb output by the optical source. In particular, a set of light sources in the optical source provide optical signals having the set of wavelengths. Moreover, the optical signals are output at diffraction angles of an optical device in the optical source (such as an echelle grating), and optical detectors in the optical source determine optical metrics associated with the optical signals. Furthermore, control logic in the optical source provides control signals to the set of light sources based on the determined optical metrics.

Abstract: A system includes optical modules. Each module includes a different base and one or more module waveguides on the base. Module waveguides from different modules are aligned such that the aligned module waveguides exchange light signals. At least a portion of one of the aligned module waveguides is between the base of one of the modules and the base of another module. First electronics operate a transmitter on a first one of the optical modules so as to generate one of the light signals. Second electronics operate a receiver on a second one of the modules such that the electronics generate an electrical signal in response to the receiver receiving one of the light signals.

Abstract: In a multi-chip module (MCM), first and second optical waveguides convey optical signals among integrated circuits. The first and second optical waveguides may be implemented in a first layer or plane on a substrate. Moreover, bridge chips in a second plane may be used to couple the optical signals between the first or second optical waveguides and the integrated circuits. By using a single layer for optical routing, the MCM may provide a point-to-point network among the integrated circuits without optical-waveguide crossing.

Abstract: An optical multiplexer/de-multiplexer (MUX/de-MUX) includes a two-dimensional pattern of features in a propagation region that conveys an optical signal having wavelengths. A given feature in this pattern has a characteristic length and the features have an average pitch, both of which are less than fundamental smallest of the wavelengths divided by an effective index of refraction of the propagation region. Moreover, an optical device in the optical MUX/de-MUX images and diffracts the optical signal using a reflective geometry, and provides the imaged and diffracted optical signal to output ports. For example, the optical device may include an echelle grating.

Abstract: An optical source includes a set of N light sources that provide a corresponding set of N optical signals having N carrier wavelengths. These optical signals are combined into a seed optical signal and transported to a substrate using an optical fiber. This substrate includes a set of K optical amplifiers that amplify the seed optical signal and provide a set of M output optical signals on a corresponding set of M output optical waveguides (where M is less than K). In this way, a total power of the set of M output optical signals may be significantly larger than that of the seed optical signal, thereby ensuring that a majority of a power efficiency of the optical source is associated with power efficiencies of the set of K optical amplifiers instead of power efficiencies of the set of N light sources.

Abstract: An optical-source monitor images and diffracts received optical signals using an optical device that has a reflective geometry. For example, the optical device may include a diffraction grating on a curved surface, such as an echelle grating. By imaging and diffracting the optical signals, the optical device may couple to the optical signals on different diffraction orders of the optical device (which have different carrier wavelengths) from input optical waveguides to corresponding output optical waveguides. Then, output power monitors may measure the output power levels of the optical signals, and control logic may provide wavelength control signals to optical sources that provide the optical signals based on measured output power levels.