Plasmonic nanolasers produce coherent light with wavelengths on a scale similar to their own or larger. In the past decade they have attracted intense interest, particularly from the emerging areas of integrated photonic circuits and biomedicine. Despite these capabilities, plasmonic nanolasers are still not completely understood, and this lack of understanding leads to confusing them with spasers and random lasers. Herein, the operation of pure spaser‐based plasmonic nanolaser arrays is presented. For this, a monolayer of silver nanoparticles (NPs) affixed to a dielectric surface and covered with a fluorescent polymethyl methacrylate (PMMA)–coumarin solid composite is investigated. The input–output characteristic measured for the composites on a bare substrate (without Ag NPs) reveals that the emission at pump pulse energies above 2.4 mJ (at 355 nm excitation wavelength) stops growing, and instead is inhibited by saturation. In contrast, in such structures with Ag NPs an additional emission band pops up over a fluorescence background. It has a spectral width order of units of nanometers and its intensity grows faster than at lower pump pulse energies, revealing a nonlinear dependence of the input–output characteristic. The spaser‐based lasing observed is completely linearly polarized and clearly directed as 45° from the substrate.
Silicon is the primary material of modern electronics. It also possesses bright potentials for applications in nanophotonics. At the same time optical properties of bulk silicon do not fully satisfy requirements imposed on them. Fortunately, properties of silicon nanostructures strongly depend on their shapes and sizes. In this regard, of special interest is the development of fabrication and post-processing methods of silicon nanostructures. In this contribution we propose a method for silicon nanostructures fabrication combining the technique of high-vacuum deposition with metal-assisted chemical etching. SEM images as well as ellipsometry, Raman scattering and optical spectroscopy data prove that the desired structural changes were obtained.
We strive to obtain highly fluorescent planar materials that may be used for the development of nanolasers based on localized plasmons. The promissing candidates for this purpose are materials consisting of mixtures of organic molecules, polymer, and silver nanoparticles. Silver nanoparticles were preliminary deposited on the quartz substrates. These samples were characterized by SEM and absorption spectroscopy. Then, they were covered by the polymer/rhodamine and polymer/coumarin layers using either spin-coating or evaporation techniques and characterized by confocal luminescent microscopy and spectroscopy. As a result of the localized surface plasmon excitation, we observed the enhancement of the rhodamine and coumarine absorption in the near fields of silver nanoparticles. The fluorescence of the thin films of polymer activated by dyes molecules with silver nanoparticles was almost 20-fold more intense than that on the bare dielectric surfaces without silver nanoparticles. In the presence Ag nanoparticles and at increased intensities of excitation we found also slight narrowing of the luminescence spectrum of polymer/coumarin layers.
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