Final Report Summary - PHOTON-PLASMONHYB (Photonic-plasmonic hybrid for optical switching and biosensing application)
The proposed project is built on our recent works that include a demonstration of selective excitation of optical waveguide modes based on phase matching condition between a plasmonic nanoantenna grating and a dielectric waveguide, a scheme to directionally excite a plasmon wave via phase engineering of nanoantennas, and a low-dispersion plasmonic-photonic coupler. Building on our expertise, we propose here to utilise the intense and localised electromagnetic field with the characterisitic decay time in the sub-picosecond regime of a plasmonic nanoantenna to achieve control over the optical response of a microring resonator. There are three main research objectives. The project aims - To enhance scientific understanding of the coupling mechanism between a metallic plasmonic nanoantenna and a dielectric ring resonator towards feasibility study of using a plasmonic nanoantenna as a local excitation source to a dielectric microring resonator. - To provide design rules for hybrid photonic-plasmonic structures using the example system of microring-nanoantenna - To demonstrate the practicality of the proposed hybrid structure in achieving optical switching and biosensing functionalities. Several research questions arise based on the research objectives of the unexplored research theme discussed above. Although there have been numerous reports indicating that coupling exists between a nanoantenna and a dielectric resonator or waveguide, there is still an open question as to how efficient and to what extent can a single nanoantenna be in such a coupling? What can we achieve and improve if we decisively place them rather than forming them into a metal grating? Will side coupling with its planar architecture be a better design than top coupling which provides better control over the coupling distance? Can the coupling be put to good use, i.e. can we demonstrate its use using a more application-oriented design? The work done so far up to the reporting period is described in more detail below. In general, the objective of this reporting period is to achieve a thorough understanding of the state of the arts in the field, directly related to the use of plasmonic nanoantenna to achieve optical modulation and sensing functionalities, and to attain the design rule based on simulation results of hybrid microring resonator-plasmonic nanoantenna design. The results obtained so far indicate that plasmonic nanoantenna can induces change to the transmission properties of the microring resonantor, and thus results in optical switching or modulation functionality. The design plays an important role and further possibilities to engineer the response of the hybrid microring resonator-plasmonic nanoantenna has been discussed. The results may pave the way to exciting way to control the interaction between dielectric resonantor and plasmonic structure in general, which are believed to find application primarily in optical sensing field as well as in fundamental research of light-matter interaction.