High-bandwidth, low-power and compact silicon electro-optical modulators are essential for future energy-efficient and densely integrated optical data communication circuits. The all-silicon plasma-dispersion-effect ring resonator modulator is an attractive prospect. However, its performance is currently limited by the trade-off between modulation depth and switching speed, dictated by its quality factor. Here we introduce a mechanism to leap beyond this limitation by harnessing the plasma absorption induced in a silicon metal–oxide–semiconductor waveguide to enhance the extinction ratio of a low-quality-factor, high-speed ring modulator. The fabricated devices demonstrate a modulation depth of ~27 dB for a bias of ~3.5 V. Modulation enhancement has been observed for operation frequencies ranging from kilohertz to gigahertz, with data modulation up to 100 Gbit s−1 on–off keying demonstrated, paving a way to the evolution of optical interconnects to 100 Gbaud and beyond per wavelength.
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This work was supported by funding from Rockley Photonics and the EPSRC through the Prosperity Partnership (EP/R003076/1), EPSRC Platform Grant (EP/N013247/1), EPSRC Strategic Equipment Grant (EP/T019697/1) and European Commission H2020 PICTURE Project (780930). D.J.T. acknowledges funding from the Royal Society for his University Research Fellowship (UF150325).
Authors A.S., G.Y., R.S., A.Z., G.R. and D.J.T. are shareholders of Rockley Photonics Holdings Limited (NYSE: RKLY), a global leader in photonics-based health monitoring and communications solutions.
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Supplementary discussion, Supplementary Figs. I-1, I-2, I-3, I-4, I-5, I-6, I-7, I-8, II-1, II-2, III-1, III-2, III-3, III-4, III-5, IV-1, IV-2 and IV-3 and Supplementary Tables III-1 and IV-1.
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Source data of bandwidth and eye diagram image of Fig. 4.
Source data of bandwidth and eye diagram image of Fig. 5.
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Zhang, W., Ebert, M., Li, K. et al. Harnessing plasma absorption in silicon MOS ring modulators. Nat. Photon. 17, 273–279 (2023). https://doi.org/10.1038/s41566-023-01159-3