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    Narrow Stimulated Resonance Raman Scattering and WGM Lasing in Small Conjugated Polymer Particles for Live Cell Tagging and Tracking
    (Weinheim : Wiley-VCH, 2020) Haehnle, Bastian; Lamla, Markus; Sparrer, Konstantin M.J.; Gather, Malte C.; Kuehne, Alexander J.C.
    Conjugated polymer particles are brightly fluorescing and stable materials for live cell imaging. Combination of conjugated polymers with a whispering gallery mode (WGM) resonator allows laser emission from microscale particles. Once internalized by cells, the mode pattern of the laser emission can be used for tagging and tracking, as each laser spectrum represents a bar code to identify individual cells. However, currently these particle systems are limited by their large size, which might interfere with cellular functions. Here, stimulated resonance Raman scattering (SRRS) in small conjugated polymer microparticles is presented as a new method for generating narrow emission as an alternative to WGM-based laser emission. This opens up spectral range for multiplexing optical readout and multicolor imaging of live cells. The synthesis of monodisperse micrometer-sized poly(fluorene-co-divinylbenzene) particles is discussed and their WGM and SRRS emission are characterized. Finally, how these particles and their emission can be employed in live cell imaging and tagging is showcased. © 2020 The Authors. Advanced Optical Materials published by Wiley-VCH GmbH
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    Recent Progress on Optoplasmonic Whispering-Gallery-Mode Microcavities
    (Weinheim : Wiley-VCH, 2021) Chen, Yongpeng; Yin, Yin; Ma, Libo; Schmidt, Oliver G.
    Optoplasmonic whispering-gallery-mode (WGM) microcavities, consisting of plasmonic nanostructures and optical microcavities, provide excellent platforms for exploring fundamental mechanisms as well as facilitating novel optoplasmonic applications. These integrated systems support hybrid modes with both subwavelength mode confinement and high-quality factor which do not exist in either pure optical WGM microcavities or plasmonic resonators. In this progress report, geometric designs and fabrication strategies of optoplasmonic microcavities, which efficiently bridge the interaction between resonant light and plasmonic resonances, are reviewed in detail. Three types of hybrid modes in the optoplasmonic microcavities, that is, surface-plasmon-polariton whispering-gallery modes, hybrid photon–plasmon whispering-gallery modes, and heterostructured metal–dielectric whispering-gallery modes, are considered. These modes are characterized by a largely enhanced evanescent field that is referred to as a plasmon-type field in hybrid whispering-gallery modes. Moreover, the coupling effect between localized surface plasmon resonances and whispering-gallery modes is summarized. The underlying coupling mechanisms and their influence on mode shifts, Q factor, mode splitting, and line shapes of the whispering-gallery modes are discussed. Applications based on optoplasmonic WGM microcavities including enhanced sensing, nanolasing, and free-space coupling are highlighted, followed by an outlook of the opportunities and challenges in developing large-scale on-chip integrated optoplasmonic systems.