Silicon microresonator adds directional control to photonic spiking neurons

Researchers published a new Opto-Electronic Sciences study on Aug. 28, 2026, describing a programmable silicon microresonator that can fire optical spikes in one direction while staying quiet in the other. The device could help photonic neural networks reduce feedback noise and better mimic how biological neurons handle signals.

Why it matters: - Photonic spiking neurons are a candidate building block for faster, lower-energy neuromorphic computing. - Directional control could reduce unwanted feedback and crosstalk in photonic neural networks. - The work points to a single silicon device that can support excitatory, inhibitory and synchronizing interactions.

What happened: - Opto-Electronic Sciences published a paper on Aug. 28, 2026, on a programmable directional photonic spiking neuron based on a non-Hermitian silicon microresonator. - The device is called DRUM, short for Dynamically Reconfigurable Unified Microresonator. - The study was led by Biasi, Aslan, Gretter and coauthors. - The paper has DOI 10.29026/oes.2026.260038.

The details: - DRUM uses a silicon ring-shaped waveguide connected to two side lobes. - Each side lobe includes two microheaters. - Small currents through the heaters tune how light exchanges between the two circulation directions inside the ring. - Driven from one direction, the ring builds enough energy to break a steady laser beam into a train of optical spikes. - Driven from the opposite direction, the same device remains quiet even when input power rises above the usual firing threshold. - The same component can operate in silent, excitable or hypersensitive regimes without changing its geometry. - Heater tuning shifts the firing threshold, changes the light-accumulation interval before a spike, and lengthens the recovery time after a spike. - A numerical model based on thermal and free-carrier effects in silicon reproduces the observed behavior. - The spike is emitted mainly in one direction, while a weaker signal reflects back toward the input. - That back-action can be electrically controlled. - Simulations of two coupled DRUMs show that one device’s reflected signal can trigger firing in the other, suppress the other device’s oscillation, or lock both devices into synchronized firing. - Those outcomes map to excitatory, inhibitory and synchronizing synaptic interactions. - The devices are fabricated in silicon with standard processes and rely on intrinsic nonlinearities rather than external gain.

Between the lines: - Conventional microresonators usually respond similarly in both directions, which limits their usefulness for brain-inspired circuits. - The DRUM design separates forward and backward behavior, closer to how biological neurons process signals. - The backward signal is not just a side effect; the study treats it as a controllable resource for shaping interactions between nodes. - That makes the architecture more flexible than a fixed-response microresonator and could make larger photonic circuits easier to stabilize.

What's next: - The authors indicate programmable directionality could help scale event-driven photonic neural networks. - The silicon platform and standard fabrication approach suggest a path toward larger integrated photonic circuits. - Further work will likely focus on network-level demonstrations and hardware integration for neuromorphic computing.

The bottom line: - DRUM combines directional firing, tunable back-action and multiple neuron-like operating modes in one silicon microresonator, bringing photonic spiking networks closer to practical neuromorphic hardware. - More information: the journal site