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T. N. Smirnova et al.
photopolymerizable composites opens the possibility to create periodic distribution
of NPs in polymer matrix by a simple one-step holographic polymerization method
[8, 9].
Due to the limited size of NPs, their electron dynamics differs substantially
from the case of bulk medium and is governed by the laws determined by both
the properties of individual metallic nanoparticles and their spatial organization
and the properties of the dielectric matrix [10–14]. This opens up the possibility
to control the nonlinear properties of nanocomposites, which is easier to implement
when using polymer matrices.
One of the ways to control the plasmon properties of nanocomposites is submicrometer scale structuring [15, 16]. Ordered structures with a submicron period
can be used for the creation of optical memory and neural networks [17], as sensors
[18], diffraction elements of a new type with ultrahigh spectral dispersion [19, 20],
or distributed feedback cavities of waveguide lasers [21].
Nowadays, nonlinear properties of NPs of various sizes and shapes are being
investigated, starting from metal clusters comprising several atoms to nanoparticles
consisting of tens of thousands of atoms. Theoretical description of the properties of
systems of different sizes requires different approaches and does not always allow
to explain and even more so to predict the results of the experiment.
Thus, despite many years of research of metal-doped nanocomposites, this
direction remains relevant both from the point of view of further development of
theory of nonlinear processes and seeking technologically simple and economically
expedient methods to create structures with required properties.
Nanocomposites are most often created using silver, gold, and copper nanoparticles. Silver NPs are of particular interest, because their absorption bands in the
optical spectral region are characterized by higher oscillator strength than that
of Au and Cu NPs [22] and references in it. Thus higher nonlinear absorption
coefficients can be expected for Ag nanoparticles compared to Au and Cu NPs under
equal conditions. In addition the overlapping of plasmon and interband absorption
bands is less pronounced for Ag nanoparticles. For them, the energy of interband
transition is of about 4 eV (the energy of plasmon resonance is approximately
2.8 eV), whereas for Au and Cu NPs, the interband transition energy is 2.3 and
2.6 eV, respectively. This allows investigating nonlinear optical processes caused
solely by surface plasmons at moderate excitation intensities.
A large number of works are devoted to the study of Ag-doped nanocomposites,
for example, [22–39], and references therein. An exhaustive bibliography of
researches performed before 2004 is given in [26]. The nonlinear properties of Ag
NP colloidal solutions [26, 27, 29], layers of Ag NPs applied to various substrates
[25], or nanoparticles incorporated in various inorganic matrices [22–24, 28, 30] and
polymers [31–38] are explored.
While earlier studies paid more attention to nonlinear properties of nanocomposites based on “neutral” matrices, characterized by extremely low nonlinear response,
recent works concentrate on the development and study of multicomponent composites, where metal NPs are used to further enhance the nonlinear response,
luminescence efficiency, and other properties. As mentioned above, polymers open
T. N. Smirnova et al.
photopolymerizable composites opens the possibility to create periodic distribution
of NPs in polymer matrix by a simple one-step holographic polymerization method
[8, 9].
Due to the limited size of NPs, their electron dynamics differs substantially
from the case of bulk medium and is governed by the laws determined by both
the properties of individual metallic nanoparticles and their spatial organization
and the properties of the dielectric matrix [10–14]. This opens up the possibility
to control the nonlinear properties of nanocomposites, which is easier to implement
when using polymer matrices.
One of the ways to control the plasmon properties of nanocomposites is submicrometer scale structuring [15, 16]. Ordered structures with a submicron period
can be used for the creation of optical memory and neural networks [17], as sensors
[18], diffraction elements of a new type with ultrahigh spectral dispersion [19, 20],
or distributed feedback cavities of waveguide lasers [21].
Nowadays, nonlinear properties of NPs of various sizes and shapes are being
investigated, starting from metal clusters comprising several atoms to nanoparticles
consisting of tens of thousands of atoms. Theoretical description of the properties of
systems of different sizes requires different approaches and does not always allow
to explain and even more so to predict the results of the experiment.
Thus, despite many years of research of metal-doped nanocomposites, this
direction remains relevant both from the point of view of further development of
theory of nonlinear processes and seeking technologically simple and economically
expedient methods to create structures with required properties.
Nanocomposites are most often created using silver, gold, and copper nanoparticles. Silver NPs are of particular interest, because their absorption bands in the
optical spectral region are characterized by higher oscillator strength than that
of Au and Cu NPs [22] and references in it. Thus higher nonlinear absorption
coefficients can be expected for Ag nanoparticles compared to Au and Cu NPs under
equal conditions. In addition the overlapping of plasmon and interband absorption
bands is less pronounced for Ag nanoparticles. For them, the energy of interband
transition is of about 4 eV (the energy of plasmon resonance is approximately
2.8 eV), whereas for Au and Cu NPs, the interband transition energy is 2.3 and
2.6 eV, respectively. This allows investigating nonlinear optical processes caused
solely by surface plasmons at moderate excitation intensities.
A large number of works are devoted to the study of Ag-doped nanocomposites,
for example, [22–39], and references therein. An exhaustive bibliography of
researches performed before 2004 is given in [26]. The nonlinear properties of Ag
NP colloidal solutions [26, 27, 29], layers of Ag NPs applied to various substrates
[25], or nanoparticles incorporated in various inorganic matrices [22–24, 28, 30] and
polymers [31–38] are explored.
While earlier studies paid more attention to nonlinear properties of nanocomposites based on “neutral” matrices, characterized by extremely low nonlinear response,
recent works concentrate on the development and study of multicomponent composites, where metal NPs are used to further enhance the nonlinear response,
luminescence efficiency, and other properties. As mentioned above, polymers open