Optoelectronic Reservoir Computing with an On-Chip True-Time-Delay Element
Abstract
Compact delay elements remain a central challenge in photonic neuromorphic processors. Here, we demonstrate an optoelectronic delayed-feedback reservoir computer that incorporates a foundry-fabricated silicon nitride (Si3N4) true-time-delay circuit within its feedback loop. Eight cascaded Archimedean spirals provide a \SI{1.76}{\metre} on-chip optical path and a calculated passive group delay of \SI{11.63}{\nano\second}. At a feedback gain of G=0.0223, the system classifies sinusoidal and square waveforms without error (word error rate, WER\,=\,0 across all cross-validation folds), predicts the Mackey--Glass chaotic series with a best-fold normalized mean-square error (NMSE) of $0.0082, and performs nine−class Japanese Vowels speaker classification with WER=$\,0.0898. We also introduce a subcarrier phase-encoding method that maps the calculated 0.232π spiral-to-reference phase contrast onto the measured reservoir states through deliberate aliasing, achieving NMSE\,=\,0.0767 and WER\,=\,0 without increasing the insertion-loss-limited feedback gain. These results show that on-chip propagation delay in Si3N4 can operate as a functional component of an optoelectronic reservoir computer and motivate lower-loss, more-integrated implementations.
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BibTeX
@misc{murad2026optoelectronic,
title = {{Optoelectronic Reservoir Computing with an On-Chip True-Time-Delay Element}},
author = {Ahmad Murad and Shadad Watad and Alina Karabchevsky},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.05907},
eprint = {2609.05907},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.05907},
}
RIS
TY - UNPB
TI - Optoelectronic Reservoir Computing with an On-Chip True-Time-Delay Element
AU - Ahmad Murad
AU - Shadad Watad
AU - Alina Karabchevsky
PY - 2026
DA - 2026/09/05
PB - arXiv
DO - 10.48550/arxiv.2609.05907
UR - https://arxiv.org/abs/2609.05907
AB - Compact delay elements remain a central challenge in photonic neuromorphic processors. Here, we demonstrate an optoelectronic delayed-feedback reservoir computer that incorporates a foundry-fabricated silicon nitride (Si_3N_4) true-time-delay circuit within its feedback loop. Eight cascaded Archimedean spirals provide a \SI{1.76}{\metre} on-chip optical path and a calculated passive group delay of \SI{11.63}{\nano\second}. At a feedback gain of G=0.0223, the system classifies sinusoidal and square waveforms without error (word error rate, WER\,=\,0 across all cross-validation folds), predicts the Mackey--Glass chaotic series with a best-fold normalized mean-square error (NMSE) of $0.0082, and performs nine−class Japanese Vowels speaker classification with WER=$\,0.0898. We also introduce a subcarrier phase-encoding method that maps the calculated 0.232π spiral-to-reference phase contrast onto the measured reservoir states through deliberate aliasing, achieving NMSE\,=\,0.0767 and WER\,=\,0 without increasing the insertion-loss-limited feedback gain. These results show that on-chip propagation delay in Si_3N_4 can operate as a functional component of an optoelectronic reservoir computer and motivate lower-loss, more-integrated implementations.
ER -