Resonance-splitting and enhanced notch depth in SOI ring resonators with mutual mode coupling
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Updated: Jul 4, 2026

Fabrication and Characterization of High-Q Silicon Nitride Membrane Resonators
Published on: August 8, 2025
Ziyang Zhang1, Matteo Dainese, Lech Wosinski
1Laboratory of Optics, Photonics and Quantum Electronics, Department of Microelectronics and Applied Physics, Royal Institute of Technology (KTH), Electrum 229, 164 40 Kista, Sweden.
Abstract:
Resonance-splitting and enhanced notch depth are experimentally demonstrated in micro-ring resonators on SOI platform as a result of the mutual mode coupling. This coupling can be generated either by the nanometer-scaled gratings along the ring sidewalls or by evanescent directional coupling between two concentric rings. The transmission spectra are fitted using the time-domain coupled mode analysis. Split-wavelength separation of 0.68 nm for the 5-microm-radius ring, notch depth of 40 dB for the 10-microm-radius ring, and intrinsic Q factor of 2.6 x 10(5) for the 20-microm-radius ring are demonstrated. Notch depth improvement larger than 25 dB has been reached in the 40-39-microm-radius double-ring structure. The enhanced notch depth and increased modal area for the concentric rings might be promising advantages for bio-sensing applications.
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