Fabrication technologies for vertically coupled microring resonator with multilevel crossing busline and ultracompact-ring radius

By Y. Kokubun, Y. Hatakeyama, Masashi Ogata, S. Suzuki, Nobuhiro Zaizen. IEEE Journal of Selected Topics in Quantum Electronics, 2005

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To eliminate the scattering loss at the crossing points of cross-grid busline waveguides, the multilevel crossing structure of the busline waveguides was introduced into a vertically coupled microring resonator (VCMRR) filter. To achieve this structure, two fabrication technologies were newly developed; one is a method to planarize perfectly the top surface of each buried waveguide, and the other is a method to fabricate microring waveguides with very smooth sidewalls. Using the latter method, an ultracompact VCMRR with a ring radius of 5 /spl mu/m was realized and a free spectral range of 37 nm was successfully demonstrated. Next, using the former method, single-ring and quadruple series-coupled ring resonators with multilevel crossing busline waveguides were fabricated. A clear filter response was obtained for the single-microring resonator, and a boxlike filter response was obtained for the quadruple series-coupled microring resonator with multilevel crossing busline waveguides.

Subfields: Atomic and Molecular Physics, and Optics, Electrical and Electronic Engineering

View Paper: https://www.semanticscholar.org/paper/4419f97717b4ecfd59ec524b028a63d614ce4e69