Efficient light coupling into a photonic crystal waveguide with flatband slow mode

A. Säynätjoki (Corresponding Author), K. Vynck, M. Mulot, D. Cassagne, Jouni Ahopelto, H. Lipsanen

    Research output: Contribution to journalArticleScientificpeer-review

    9 Citations (Scopus)

    Abstract

    We design an efficient coupler to transmit light from a strip waveguide into the flatband slow mode of a photonic crystal waveguide with ring-shaped holes. The coupler is a section of a photonic crystal waveguide with a higher group velocity, obtained by different ring dimensions. We demonstrate coupling efficiency in excess of 95% over the 8 nm wavelength range where the photonic crystal waveguide exhibits a quasi-constant group velocity vgc/37 and observe a more than 12-fold intensity enhancement in the slow-light waveguide. An analysis based on the small Fabry–Pérot resonances in the simulated transmission spectra is used for studying the effect of the coupler length and for evaluating the coupling efficiency in different parts of the coupler. The mode conversion efficiency within the coupler is more than 99.7% over the wavelength range of interest. The parasitic reflectance in the coupler, which depends on the propagation constant mismatch between the slow mode and the coupler mode, is lower than 0.6%.
    Original languageEnglish
    Pages (from-to)127 - 133
    Number of pages7
    JournalPhotonics and Nanostructures: Fundamentals and Applications
    Volume6
    Issue number2
    DOIs
    Publication statusPublished - 2008
    MoE publication typeA1 Journal article-refereed

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    Keywords

    • Guided waves
    • Integrated optics materials
    • Optical systems design
    • Waveguide
    • Photonic integrated circuits
    • Dispersion
    • Photonic crystal

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