Carbon dots are attracting much attention because of their low toxicity, biocompatibility, and photostability. In this study, we fabricate carbon dot-metal nanoparticle composites using electron-beam-induced chemical reactions to improve the photoluminescence characteristics. We investigate the spectral characteristics of the composites by linear and nonlinear optical spectroscopy. The composites show plasmon resonance depending on the material used. The linear and nonlinear photoluminescence from the composites are enhanced by plasmon excitations, and the enhancement reaches nearly several times and 20 times, respectively. We also fabricate nanowire structures containing the composites. The structures show very intense photoluminescence and unique polarization characteristics depending on the wire width. We reveal that the polarization characteristics originate from the plasmonic coupling along the short axis of the wire. The technique developed in this study is promising for the polarization control of light-emitting elements and the creation of new functional nanomaterials.
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