It has been experimentally shown that the thresholds of non-resonator laser generation in heterogeneous planar active media in solutions with nanoparticles of gold, platinum and silver practically coincide. The excess energy obtained by plasmon resonance does not affect the lowering of laser generation thresholds but is spent on heating the nanoparticles.
The paper presents the results of numerical simulation of the dispersion properties of surface plasmon-polaritons at the interface between an active composite medium based on metallic nanoparticles and a substrate of the same metals in the visible wavelength range. It is shown that the amplification and dispersion properties of surface plasmon polaritons in these structures can be varied within wide limits by varying the concentration of nanoparticles.
The studies have shown that films with different thicknesses, but practically identical transmittance values, give absolutely different results. This suggests that in addition to transmission, the generation characteristics are significantly affected by the thickness of the matrix being researched.
The cross-sections of attenuation, scattering and absorption of spherically aggregated metal nanoparticles in dependence on the aggregate size, the degree of its filling with nanoparticles and physical properties of nanoparticle material have been estimated, according to the model of the effective medium and the theory of G. Mie. In that case, the concentration of the nanoparticles changes radially.
The paper presents the results of the Helmholtz equation solution by the method of perturbation theory in the spherical coordinate system for the Debye potentials for weakly heterogeneous media based on metal nanoparticles and the dielectric matrix. In that case, the dielectric function of a composite changes in space in the radial direction.
The paper gives the results of computer simulating reflectivity of a flat structure made of composite material on the basis of Ag, Ni, Al, Cu nanoparticles and a substrate of the same metals within the visible wavelength range. The possibility of broadband optical antireflection of a metal surface using nanoparticles of the same metals by forming in the near surface layer of the metal being made anti-reflecting a composite layer is researched. Within the visible wavelength range the dispersion characteristics of the reflectivity of the composite metal-dielectric layer on a metal substrate have been calculated for different values of the filling factor and the thickness of the composite layer both for the metals having plasmon resonances (Ag, Cu) within the visible range and for the metals plasmon resonances of which do not fall in the visible wavelength range (Al, Ni).
The paper presents the results of researching surface plasmon polaritons dispersion on the "composite medium and metal substrate" border within a visible wavelength range. The composite dielectric function varies in space according to the periodic law. The solution to this problem has been presented as an inhomogeneous wave for which the field amplitude distribution has been written in an analytical form and dispersion relations have been obtained.
In the paper comparative evaluation of the photon mean free path in the system of metal nanoparticles and dielectric matrix is performed by means of numerical simulations. As a material of nanoparticles both metals (Ag, Cu) in which the frequency of plasmon resonance falls in the range under study and metals (Al, Ni) in which the plasmon resonance frequency is far from the investigated range have been used. The research has shown that for the studied metals the media based on Al nanoparticles satisfy best the Ioffe-Regel criterion for photons of visible wavelength range.
The article presents the results of computing simulation of surface plasmon-polaritons’ dispersive properties at the interface between «a composite medium based on Al, Ag, Ni, Cu nanoparticles and a substrate made of the same metals» in the visible wavelength band. It is shown that the surface plasmon-polaritons’ dispersive properties in these structures can be changed in a wide range by altering the nanoparticles concentration.
On the basis of an analytical solution of a one-dimensional (in cylindrical coordinates) heat equation homogeneous medium with a heat source, due to the linear absorption of light, we obtained analytical expressions for the calculation of space-time profiles of the increment of temperature in heterogeneous media based on metallic nanoparticles and a dielectric matrix.
According to the model of the effective medium and G. Mie theory, attenuation cross-sections, cross-sections for scattering and absorption for metal nanoparticles nanosized aggregates have been assessed depending on the aggregate’s size , level of the aggregate’s filling with nanoparticles and physical properties of the nanoparticles material.
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