Abstract: In a multi-chip module (MCM), integrated circuits are coupled by optical waveguides. These integrated circuits receive optical signals from a set of light sources which have fixed carrier wavelengths. Moreover, a given integrated circuit includes: a transmitter that modulates at least one of the optical signals when transmitting information to at least another of the integrated circuits; and a receiver that receives at least one modulated optical signal having one of the carrier wavelengths when receiving information from at least the other of the integrated circuits. Furthermore, the MCM includes tunable drop filters optically coupled to the optical waveguides and associated integrated circuits, wherein the tunable drop filters pass adjustable bands of wavelengths to receivers in the integrated circuits. Additionally, control logic in the MCM provides a control signal to the tunable drop filters to specify the adjustable bands of wavelengths.

Abstract: A laser source includes a semiconductor optical amplifier (SOA) as a gain medium that receives and amplifies an optical signal characterized by at least a wavelength associated with a lasing mode of the laser source. This laser source includes a first optical waveguide and a second optical waveguide optically coupled to the SOA. Furthermore, a wavelength-selective reflector is optically coupled to the first optical waveguide and the second optical waveguide, where a closed loop defined by the SOA, the first optical waveguide, the wavelength-selective reflector and the second optical waveguide defines a cavity of the laser source.

Abstract: An integrated circuit that includes an optical waveguide to convey an optical signal via an optical mode in an on-chip optical waveguide is described. In this integrated circuit, a cross-sectional area of the optical waveguide may be tapered in proximity to an electro-optic modulator in the integrated circuit, such as a germanium electro-optic modulator or a quantum-well (QW) electro-optic modulator. In particular, the cross-sectional area may be tapered from a first diameter distal from the electro-optic modulator to a second diameter proximate to the electro-optic modulator. This so-called ‘inverse taper’ may increase the spatial extent or size of the optical mode, thereby allowing the optical signal to be optically coupled to or from the electro-optic modulator with low optical loss.

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: Embodiments of a bidirectional 3-way optical splitter are described. This bidirectional 3-way optical splitter includes an optical splitter having: a first external node, a second external node, a third external node, and a fourth external node. In one mode of operation, the optical splitter may be configured to receive an external input optical signal on the first external node and to provide external output optical signals on the other external nodes. Moreover, in another mode of operation, the optical splitter may be configured to receive the external input optical signal on the third external node and to provide the external output optical signals on the other external nodes.

Abstract: A system including first and second sending nodes, a horizontal optical data link (ODL) having optical signals propagating in opposite directions in first and second waveguide segments, a vertical ODL having optical signals propagating in the same direction throughout third and fourth waveguide segments, a first optical output switch operatively connecting the first sending node and the first waveguide segment and configured to switch first data item onto the first waveguide segment during a first timeslot, a second optical output switch operatively connecting the second sending node and the second waveguide segment and configured to switch second data item onto the second waveguide segment during a second timeslot, and an optical coupler pair operatively connecting the first and second waveguide segments to the third and fourth waveguide segments, respectively, and redirecting the first and the second data items from the horizontal to the vertical ODL.

Abstract: A system for transmitting data, including: a transmitter node having a setup path packet and multiple data packets; a receiver node connected to the transmitter node by a first optical channel (OC); and a first intermediate node having a first forwarding module and connected to the transmitter node by a second OC and to the receiver node by a third OC, where the transmitter node transmits the setup path packet and a first subset of the multiple data packets to the first intermediate node using the second OC, where the first forwarding module relays, in response to receiving the setup packet, the first subset to the receiver node by switching the first subset from the second OC to the third OC, and where the receiver node receives a second subset of the multiple data packets from the transmitter node using the first OC.

Abstract: An optical multiplexer/demultiplexer is described. In this optical multiplexer/demultiplexer, multiple coupled-waveguide grating devices are optically coupled to a bus optical waveguide. A given coupled-waveguide grating device has a band-pass filter characteristic that encompasses multiple optical channels, thereby providing coarse optical filtering. Moreover, the optical multiplexer/demultiplexer includes multiple add/drop filters (such as ring resonators) that optically couple to the coupled-waveguide grating devices. A given add/drop filter has a filter bandwidth corresponding to a given optical channel, thereby providing fine optical filtering. Furthermore, the band-pass filter characteristic of the given coupled-waveguide grating device is approximately equal to or less than a free spectral range (FSR) of the given add/drop filter.

Abstract: A multi-chip module (MCM), which includes a three-dimensional (3D) stack of chips that are coupled using optical interconnects, is described. In this MCM, disposed on a first surface of a middle chip in the 3D 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. Moreover, 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. Note that an optical path associated with the second direction passes through an opening in a substrate in the middle chip.

Abstract: An optical switch is described that includes two optical waveguides, which are defined in a semiconductor layer, positioned proximate to an intermediate component, such as a micro-resonator or a directional coupler. Material underneath a portion of either or both optical waveguides is removed so that the portion of either or both optical waveguides is free standing, and a group of electrodes is proximate to the free-standing portion of either or both optical waveguides. During operation of the optical switch, a spacing-control circuit applies an electrical signal to the group of electrodes. An electrostatic force associated with the electrical signal modifies a spacing between the free-standing portion of either or both optical waveguides and the intermediate component, thereby substantially increasing optical coupling between either or both optical waveguides and the intermediate component to convey a broadband optical signal between the optical waveguides.

Abstract: An integrated circuit that includes an optical waveguide defined in a semiconductor layer is described. In this integrated circuit, light is coupled between the optical waveguide and an optical modulator, which is disposed on the optical waveguide, using 3-dimensional (3-D) taper structures that are proximate to the ends of the optical modulator. The cross-sectional areas of these 3-D taper structures transition, over a distance, from that of the optical waveguide (distal from the optical modulator) to that of optical modulator (proximate to the ends of the optical modulator). In this way, a spatial extent of an optical mode in the optical waveguide and a spatial extent of the optical mode in the optical modulator may be approximately matched to reduce the optical loss when the light is coupled to or from the optical modulator.

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: In a laser source, a first optical waveguide includes a gain medium, and a second optical waveguide includes a phase tuner which adjusts a phase value of the phase tuner to specify the wavelength of the laser source. Furthermore, the laser source includes a first ring resonator and a second ring resonator, which, respectively, are optically coupled to the first optical waveguide and the second optical waveguide at opposite ends of the laser source. In particular, coupling wavelengths of the first and second ring resonators may match a wavelength of the optical signal, thereby defining an optical resonance cavity in the laser source and selecting a laser mode of the laser source which is associated with the wavelength. Additionally, the laser source includes an optical amplifier that receives and amplifies the optical signal output from the optical resonance cavity.

Abstract: During operation of an electro-absorption modulator, an optical signal is conveyed, using an optical waveguide in the electro-absorption modulator, to a semiconductor layer that substantially fills a gap between two portions of the optical waveguide. Then, the optical signal is electro-absorption modulated by selectively applying a voltage to electrodes that produces an electric field, approximately perpendicular to the midline of the optical waveguide, in the semiconductor layer. These electrodes are coupled to the edges of the semiconductor layer at the periphery along the width of the semiconductor layer by intervening layers. Furthermore, the intervening layers include a material that has a lower index of refraction than the semiconductor layer, and a lower optical absorption than the electrodes.

Abstract: A multi-chip module (MCM) is described. This MCM includes multiple sites, where a given site in the multiple sites includes multiple chips with proximity connectors that communicate information through proximity communication within the MCM via multiple components associated with the given site. Note that the MCM includes global redundancy and local redundancy at the given site. In particular, the global redundancy involves providing one or more redundant sites in the multiple sites. Furthermore, the local redundancy involves providing one or more redundant chips in the multiple chips and one or more redundant components in the multiple components.

Abstract: An optical device that includes multiple optical modulators having actual operating wavelengths at a given temperature is described. Because of differences between the actual operating wavelengths and target operating wavelengths of the optical modulators, heating elements may be used to thermally 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 thermal tuning energy associated with the heating elements.

Abstract: Embodiments of an optical device, an array of optical devices, and a technique for fabricating the optical device or the array are described. This optical device is implemented on a substrate (such as silicon), and includes a thermally tunable optical waveguide with a high thermal resistance to the surrounding external environment and a low thermal resistance to a localized heater. In particular, the thermal resistances associated with thermal dissipation paths from a heater in the optical device to an external environment via electrodes and via the substrate are increased, while the thermal resistance between the optical waveguide and the heater is decreased.

Abstract: Embodiments of an optical device, an array of optical devices, and a technique for fabricating the optical device or the array are described. This optical device is implemented on a substrate (such as silicon), and includes a thermally tunable optical waveguide that has good thermal isolation from its surroundings. In particular, a portion of a semiconductor in the optical device, which includes the optical waveguide, is free standing above a gap between the semiconductor layer and the substrate. By reducing the thermal coupling between the optical waveguide and the external environment, the optical device can be thermally tuned with significantly less power consumption.

Abstract: A multi-chip module (MCM) is described. This MCM includes two substrates having facing surfaces. Disposed on a surface of a first of these substrates, there is an optical waveguide, having an eigenmode in the plane of the surface, and an optical coupler, which redirects optical signals to and/or from the optical waveguide and a direction normal to the surface. Furthermore, disposed on a surface of a second of the substrates, which faces the surface of the first substrate, and which overlaps the optical coupler, there is an optoelectronic device. This optoelectronic device, which has an eigenmode in a direction perpendicular to the surface of the second substrate, selectively receives or provides the optical signal to and/or from the optical coupler. For example, the selective receiving or providing may be controlled by selectively applying a potential to the quantum-well device, thereby changing the optical properties of the optoelectronic device.

Abstract: A method of detecting transmission collisions in an optical data interconnect system. The method includes initiating a data transmission of a data signal from a transmitting node over the optical data channel, transmitting a first collision detect signal from the transmitting node throughout a duration of the data transmission where the first collision detect signal is transmitted over an optical detection channel corresponding to the transmitting node, monitoring at the transmitting node of the optical data interconnect system for a predetermined period of time, where the optical data interconnect system further includes optical collision detection channels corresponding to each of a plurality of receiving nodes and one or more remaining nodes, and identifying a transmission collision when a second collision signal is received through one of the optical collision detection channels at the transmitting node during the predetermined period of time.