VTT's micron-scale silicon rib+strip waveguide platform

Timo Aalto, Mikko Harjanne, Matteo Cherchi

    Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

    6 Citations (Scopus)


    Silicon rib waveguides enable single-mode (SM) operation even with the combination of multi-micron core dimensions and high refractive index contrast. In such large waveguides the optical mode field is almost completely confined inside the Si core, which leads to small propagation losses and small polarization dependency. The unique SM condition of the rib waveguide also enables the use of an ultra-wide wavelength range, for example from 1.2 to <1.7 μm, without sacrificing either SM operation or low propagation loss. This makes micron-scale Si waveguides particularly well-suited for spectroscopy and extensive wavelength division multiplexing. However, rib waveguides require large bending radii, which lead to large circuit sizes. There are two solutions for this. So-called Euler bends in Si strip waveguides enable low-loss bends down to 1 μm bending radius with less than 0.1 dB/90° loss for both polarizations. Another alternative is a total-internal reflection mirror that can have loss as low as 0.1 dB for both polarizations in either strip or rib waveguides. The excitation of higher order modes in large strip waveguides is avoided by using adiabatic rib-strip converters and low-loss components. With rib and strip waveguides it is possible to reach a unique combination of low loss, extremely small footprint, small polarization dependency, ultra-wide bandwidth and tolerance to high optical powers.

    Original languageEnglish
    Title of host publicationSilicon Photonics and Photonic Integrated Circuits V
    PublisherInternational Society for Optics and Photonics SPIE
    ISBN (Electronic)9781510601369
    Publication statusPublished - 1 Jan 2016
    MoE publication typeA4 Article in a conference publication
    EventSilicon Photonics and Photonic Integrated Circuits V - Brussels, Belgium
    Duration: 3 Apr 20167 Apr 2016

    Publication series

    SeriesProceedings of SPIE


    ConferenceSilicon Photonics and Photonic Integrated Circuits V


    • Multi-project wafer (MPW) runs
    • Rib waveguides
    • Silicon photonics
    • Silicon-on-insulator


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