Reciprocal transmissions and asymmetric modal distributions in waveguide-coupled spiral-shaped microdisk resonators

Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Chiu-lung, Kowloon City, Hong Kong
Optics Express (Impact Factor: 3.53). 11/2007; 15(22):14650-66. DOI: 10.1364/OE.15.014650
Source: PubMed

ABSTRACT We report transmission spectra and mode-field distributions of a waveguide-coupled spiral-shaped microdisk resonator on a silicon nitride-on-silica substrate. Our measured and simulated transmission spectra reveal reciprocal transmissions between clockwise and counterclockwise travelingwaves of such microcavity that lacks mirror symmetry. Our measured out-of-plane scattering intensity distributions and simulated steady-state mode-field patterns, however, indicate asymmetric modal distributions that depend on the sense of lightwave circulations and the input-coupling mechanisms. We discuss implications of the observed reciprocal transmissions with asymmetric modal distributions to unidirectional lasing from spiral-shaped microcavities reported in the literature.

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