Multi-chip electro-photonic networks and photonic memory fabrics for interconnecting multiple circuit packages
Multi-chip electro-photonic networks for interconnecting multiple circuit packages via photonic channels. Examples of a computing system include a first circuit package, a second circuit package, and one or more inter-chip bidirectional photonic channels interconnecting the first and second circuit packages. The first circuit package can include one or more memory nodes. The second circuit package can include multiple compute nodes and intra-chip bidirectional photonic channels interconnecting the compute nodes.
1 . A system, comprising:
a photonic integrated circuit comprising a plurality of optical links, each comprising:
an optical modulator configured to impart a message onto an optical signal;
a photodetector configured to convert the optical signal into an electrical signal carrying the message; and
an optical transmission medium comprising an optical waveguide connecting the optical modulator to the photodetector; and
a fabric implemented by a plurality of electronic integrated circuits mounted on the photonic integrated circuit, the fabric comprising, for each optical link, a transmit unit associated with a first of the plurality of electronic integrated circuits for sending the message from the first electronic integrated circuit and a receive unit associated with a second of the plurality of electronic integrated circuits for receiving the message sent to the second electronic integrated circuit,
wherein the transmit unit comprises:
a driver electrically connected to the optical modulator of the optical link, the driver configured to apply an electronic drive signal to the optical modulator; and
a serializer configured to convert the message received as parallel data into the electronic drive signal for driving the optical modulator; and
wherein the receive unit comprises:
an amplifier electrically connected to the photodetector of the optical link, the amplifier configured to amplify the electronic signal output by the photodetector;
gain control configured to normalize a signal level of the electronic signal;
a slicer configured to extract a bitstream from the electronic signal; and
a deserializer configured to convert the message contained in the bitstream back into the parallel data.
2 . The system of claim 1 , further comprising an optical coupling structure optically coupling the waveguide to an optical fiber.
3 . The system of claim 2 , wherein the photonic integrated circuit further comprises a splitter combining a set of optical links into the optical coupling structure.
4 . The system of claim 2 , wherein the optical coupling structure comprises an edge coupler.
5 . The system of claim 4 , wherein the optical fiber is part of an array of optical fibers assembled into a ribbon fiber.
6 . The system of claim 1 , wherein each optical modulator is an electro-absorption modulator, a Mach-Zehnder modulator, or a ring modulator.
7 . The system of claim 1 , wherein a distance between each driver and its associated optical modulator is smaller than 200 μm.
8 . The system of claim 1 , wherein each photodetector is a photodiode.
9 . The system of claim 1 , wherein:
the fabric comprises a plurality of optical ports each comprising:
the transmit unit for a first of the plurality of optical links;
the receive unit for a second of the plurality of optical links;
a buffer configured to store the message arriving at the receive unit; and
a credit register configured to transmit a credit message at the transmit unit when the message is removed from the buffer, and
each electronic integrated circuit is associated with one or more of the plurality of optical ports for sending the message from the electronic integrated circuit or receiving the message sent to the electronic integrated circuit.
10 . The system of claim 9 , wherein a first optical link and a second optical link of the plurality of optical links form a bidirectional photonic channel between the first electronic integrated circuit and the second electronic integrated circuit.
11 . The system of claim 1 , wherein each electronic integrated circuit comprises the one or more optical ports associated with the electronic integrated circuit.
12 . The system of claim 11 , wherein each electronic integrated circuit comprises:
a processing element; and
a message router comprising:
a plurality of ports including:
the one or more optical ports associated with the electronic integrated circuit; and
an electronic port electrically connected to the processing element; and
a router control unit configured to grant access to an egress port among the plurality ports of the message router based on a destination address of the message and a routing policy.
13 . The system of claim 12 , wherein each optical port of each message router further comprises:
an address router unit configured to extract the destination address from the message arriving at the receive unit of the optical port; and
an output multiplexer configured to select the egress port among the plurality of ports of the message router based on the destination address of the message and the routing policy.
14 . The system of claim 12 , wherein each electronic integrated circuit further comprises an electronic interface controller connecting the processing element to the electronic port of the message router.
15 . The system of claim 12 , wherein the processing element of each electronic integrated circuit comprises:
the message router of the electronic integrated circuit; and
a plurality of processing engines electrically connected to the electronic port of the message router, the plurality of processing engines including:
a dot product engine implementing a combinatorial tree of multipliers and adders for computing dot products between vectors; and
a tensor engine for obtaining and processing vectors computed as output by the dot product engine.
16 . The system of claim 1 , wherein a distance between each photodetector and its associated amplifier is smaller than 200 μm.
17 . The system of claim 1 , wherein each amplifier is a transimpedance amplifier.
18 . The system of claim 1 , wherein each electronic integrated circuit is an electronic integrated circuit.