Engineering Plasmonic Lasing from Visible to Near-infrared Wavelength

Li, Ran

doi:https://doi.org/10.21985/n2-9h8r-3564

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Engineering Plasmonic Lasing from Visible to Near-infrared Wavelength

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Light trapping with standing waves has been achieved using photonic bandgap crystals, metal-dielectric waveguides and periodic metal nanocavity arrays. Compared with photonic materials, plasmonic metal nanocavities can provide light confinement at the sub-wavelength scale with strong near-field electric enhancement. The localized surface plasmons of individual metal nanoparticles can collectively couple to the diffraction modes from the lattice geometry, giving rise to surface lattice resonances. Surface lattice resonances can serve as optical feedback for plasmonic nanolasing at room temperature. By engineering the unit cell or lattice geometry of a plasmonic nanoparticle array, we are able to manipulate the coupling mechanisms of the plasmonic nanoparticles, leading to the realization of a plasmonic nanolaser with distinct hotspot regions. In Chapter 1, we discuss how the coupling between plasmonic nanocavities changes with lattice geometries. We fabricated plasmonic aluminum nanoparticles on Polydimethylsiloxane substrate and investigated the optical responses under different stretching conditions. Chapter 2 describes the linear and nonlinear properties of plasmonic nanoparticle arrays fabricated using different plasmonic materials. We achieved sharp surface lattice resonances with Au and Al nanoparticle arrays and integrated organic dye molecules to the arrays to compare the lasing emissions and ultrafast dynamic behaviors between different plasmonic materials. Chapter 3 shows the realization of multicolor lasers on a single device. By mixing two or three different dye solutions, we can broaden the photoluminescence of the dye gain media to spectrally overlap with different surface lattice resonances simultaneously. By stacking two plasmonic nanoparticle lattices with different periodicities and incorporating mixed dye solutions between the lattices, we obtained blue, green and red color lasing emissions at the same time, which can be potentially used to achieve a plasmonic white color laser. Chapters 4 and 5 discuss the coupling mechanism in hexagonal and honeycomb lattices at different high-symmetry points. Chapter 4 presents the distinct coupling in plasmonic honeycomb lattices caused by the non-Bravais nature of a honeycomb lattice. We discovered that the surface lattice resonance at the Γ point of a honeycomb lattice has in-plane dipole coupling hybridized with in-plane quadrupole coupling, while the surface lattice resonance at the Γ of hexagonal lattice only shows in-plane dipole coupling. Besides looking the surface lattice resonance at the Γ point, we also investigated the surface lattice resonance at the off-normal M point in Chapter 5. Out-of-plane dipole coupling was revealed in a hexagonal array and high order coupling leads to mode splitting at the M point of honeycomb lattice. These findings show the importance of the non-Bravais nature in a unit cell to the near-field coupling of plasmonic nanostructures.

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