Nanophotonic Cavity Based Synapse for Scalable Photonic Neural Networks

Aashu Jha, Chaoran Huang, Thomas Ferreira Delima, Hsuan Tung Peng, Bhavin Shastri, Paul R. Prucnal

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


The bandwidth and energy demands of neural networks has spurred tremendous interest in developing novel neuromorphic hardware, including photonic integrated circuits. Although an optical waveguide can accommodate hundreds of channels with THz bandwidth, the channel count of photonic systems is always bottlenecked by the devices within. In WDM-based photonic neural networks, the synapses, i.e. network interconnections, are typically realized by microring resonators (MRRs), where the WDM channel count (N) is bounded by the free-spectral range of the MRRs. For typical Si MRRs, we estimate N ≤ 30 within the C-band. This not only restrains the aggregate throughput of the neural network but also makes applications with high input dimensions unfeasible. We experimentally demonstrate that photonic crystal nanobeam based synapses can be FSR-free within C-band, eliminating the bound on channel count. This increases data throughput as well as enables applications with high-dimensional inputs like natural language processing and high resolution image processing. In addition, the smaller physical footprint of photonic crystal nanobeam cavities offers higher tuning energy efficiency and a higher compute density than MRRs. Nanophotonic cavity based synapse thus offers a path towards realizing highly scalable photonic neural networks.

Original languageEnglish (US)
Article number6100908
JournalIEEE Journal of Selected Topics in Quantum Electronics
Issue number6
StatePublished - 2022

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics
  • Electrical and Electronic Engineering


  • Photonic integrated circuits
  • photonic neural networks


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