Comparison of different types of MMI-resonators fabricated on a micron-scale SOI platform

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    Abstract

    1x1 optical resonators have been designed based on multi-mode interference (MMI) splitters of different splitting ratios (85:25 and 73:27) and different types of back-reflectors as feedback mechanism. They are basically 2x2 MMIs of uneven splitting ratios with one of the ports from both sides ending in a reflector. The chosen reflectors include metal-dielectric mirrors, waveguide loops and MMI reflectors. The remaining two ports play the role of input and thru port respectively. The resonant wavelengths are reflected back in the input port, hence acting also as output port in reflection. The devices have been fabricated on SOI wafers with a 3 µm-thick silicon layer. In all cases, the quality factors of the resonances of a given resonator have been found to significantly change form peak to peak. This can be attributed to wavelength dependent losses in the feedback mechanisms, that is wavelength dependent reflectivity of the back-reflectors. Through a suitable transfer matrix model, we have found that best performing devices correspond to reflectivity as high as 92% for the metal/dielectric mirrors and 88% for the MMI reflectors, corresponding to a resonator finesse of 13.1 and 9.9 respectively. The free spectral ranges of the resonators vary from about 3 nm to about 1 nm, depending on the cavity length, which is constrained by the lengths of both the MMIs and the reflectors. When suitably combined with gain elements, the proposed resonators are promising candidates as fabrication tolerant wavelength selective reflectors for external cavity lasers.
    Original languageEnglish
    Title of host publicationSilicon Photonics X
    EditorsGraham T. Reed, Michael R. Watts
    PublisherInternational Society for Optics and Photonics SPIE
    ISBN (Print)978-1-6284-1457-8
    DOIs
    Publication statusPublished - 27 Feb 2015
    MoE publication typeA4 Article in a conference publication
    EventSilicon Photonics X - San Francisco, United States
    Duration: 9 Feb 201512 Feb 2015

    Publication series

    SeriesProceedings of SPIE
    Volume9367
    ISSN0277-786X

    Conference

    ConferenceSilicon Photonics X
    Abbreviated titleSPIE OPTO
    CountryUnited States
    CitySan Francisco
    Period9/02/1512/02/15

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    Keywords

    • integrated optics
    • multimode interference splitters
    • optical resonators
    • photonic integrated circuits
    • silicon photonics

    Cite this

    Cherchi, M., Harjanne, M., Ylinen, S., Kapulainen, M., Vehmas, T., & Aalto, T. (2015). Comparison of different types of MMI-resonators fabricated on a micron-scale SOI platform. In G. T. Reed, & M. R. Watts (Eds.), Silicon Photonics X [936713] International Society for Optics and Photonics SPIE. Proceedings of SPIE, Vol.. 9367 https://doi.org/10.1117/12.2079606