Coherent photonic computing architectures

A computing system comprising:

• a photonic integrated circuit (PIC) implementing one or more computational layers, the PIC comprising:
• one or more coherent photonic crossbars each configured to modulate a plurality of optical input signals to impart computational weights associated with a plurality of sets of weights onto the optical input signals to create weighted optical input signals, and to coherently combine the weighted optical input signals to generate optical output signals encoding computational outputs associated with the plurality of sets of weights,
• at least one of the one or more coherent photonic crossbars comprising a plurality of electronically controlled modulators to impart computational inputs onto coherent optical carrier signals to generate the plurality of optical input signals, and
• at least one of the one or more coherent photonic crossbars comprising a plurality of photodetectors to generate analog electronic output signals based on the optical output signals;
• and
• a mixed-signal electronic integrated circuit (EIC) comprising:
• driver circuitry to control the modulators in the PIC in accordance with the computational inputs, and
• processing circuitry to process the analog electronic output signals, the processing being performed at least partially digitally.