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Updated: May 12, 2026

Microwave Photonics Systems Based on Whispering-gallery-mode Resonators
Published on: August 5, 2013
Coupling modulation of microrings at rates beyond the linewidth limit
W D Sacher1, W M J Green, S Assefa
1Department of Electrical and Computer Engineering and Institute for Optical Sciences, University of Toronto, 10 King’s College Road, Toronto, Ontario, M5S 3G4, Canada. wesley.sacher@mail.utoronto.ca
Abstract:
We demonstrate optical modulation rates exceeding the conventional cavity linewidth limit using a silicon coupling modulated microring. Small-signal measurements show coupling modulation was free of the parasitic cavity linewidth limitations at rates at least 6× the cavity linewidth. Eye diagram measurements show coupling modulation achieved data rates > 2× the rate attainable by conventional intracavity phase modulation. We propose to use DC-balanced encoding to mitigate the inter-symbol interference in coupling modulation. Analysis shows that coupling modulation can be more efficient than intracavity modulation for large output swings and high-Q resonators. Coupling modulation enables very high-Q resonant modulators to be simultaneously low-power and high-speed, features which are mutually incompatible in typical resonant modulators studied to date.
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