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@@ -540,8 +540,8 @@ license.
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permittivity corresponding to each stage is shown in
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Fig.~\ref{plasma-grid}.
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- To describe all the stages of light non-linear interaction with
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- Si NP, we present the calculation results obtained by using Maxwell's
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+ To describe all the stages of light non-linear interaction with Si
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+ NP, we present the calculation results obtained by using Maxwell's
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equations coupled with electron kinetics equations for different
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radii for resonant and non-resonant conditions. In this case, the
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geometry of the EHP distribution can strongly deviate from the
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@@ -550,26 +550,28 @@ license.
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nonlinear effects, taking place due to transient optical changes in
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Si. The non-stationary intensity deposition results in different time
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delays for exciting electric and magnetic resonances inside Si NP
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- because of different quality factors $Q$ of the resonances. In
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- particular, magnetic dipole resonance (\textit{b1}) has $Q \approx
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- 8$, whereas electric one (\textit{a1}) has $Q \approx 4$. The larger
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- particle supporting magnetic quadrupole resonance (\textit{b2})
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- demonstrates \textit{Q} $\approx 40$. As soon as the electromagnetic
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- wave period at $\lambda$~=~800~nm is 2.6~\textit{fs}, one needs about
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- 10~\textit{fs} to pump the electric dipole, 20~\textit{fs} for the
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- magnetic dipole, and about 100~\textit{fs} for the magnetic
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- quadrupole. According to these considerations, the first optical
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- cycles taking place on few-femtosecond scale result in the excitation
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- of the low-\textit{Q} electric dipole resonance independently on the
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- exact size of NPs and with the EHP concentration mostly on the front
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- side of the NPs. We address to this phenomena as \textit{'Stage 1'},
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- as shown in Figs.~\ref{plasma-grid} and~\ref{plasma-grid}. The first stage at the
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- first optical cycle demonstrates the dominant electric dipole
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- resonance effect on the intensity/EHP density distribution inside the
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- NPs in Fig.~\ref{plasma-grid}(a,e,j) and~\ref{time-evolution}. The larger the NPs size
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- is, the higher the NP asymmetry $G_{N_e}$ is achieved.
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-
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- \textit{'Stage 2'} corresponds to further electric field oscillations
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+ because of different quality factors $Q$ of the resonances.
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+
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+ In particular, magnetic dipole resonance (\textit{b1}) has
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+ $Q \approx 8$, whereas electric one (\textit{a1}) has $Q \approx
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+ 4$. The larger particle supporting magnetic quadrupole resonance
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+ (\textit{b2}) demonstrates \textit{Q} $\approx 40$. As soon as the
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+ electromagnetic wave period at $\lambda$~=~800~nm is 2.6~\textit{fs},
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+ one needs about 10~\textit{fs} to pump the electric dipole,
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+ 20~\textit{fs} for the magnetic dipole, and about 100~\textit{fs} for
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+ the magnetic quadrupole. According to these considerations, after few
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+ optical cycles taking place on a 10~\textit{fs} scale it results in
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+ the excitation of the low-\textit{Q} electric dipole resonance
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+ independently on the exact size of NPs. Moreover, during the first
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+ optical cycle there is no multiple mode structure inside of NP, which
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+ results into a very similar field distribution for all size of NP
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+ under consideration. We address to this phenomena as
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+ \textit{'Stage~1'}, as shown in Figs.~\ref{plasma-grid}(a,e,i).
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+ and~\ref{plasma-grid}. The first stage at the first optical cycle
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+ demonstrates the initial penetration of electromagnetic fild into the
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+ NP.
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+
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+ \textit{'Stage~2'} corresponds to further electric field oscillations
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($t \approx 2\div15$) leading to the unstationery EHP evolution
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with a maximum of the EHP distribution in the front side of the Si NP
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owing to the starting excitation of MD and MQ resonances that require more
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@@ -579,7 +581,7 @@ license.
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A number of optical cycles ($>$10 or $t>$25~\textit{fs}) is necessary
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to achieve the stationary intensity pattern corresponding to the
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- Mie-based intensity distribution at the \textit{'Stage $3$'} (see
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+ Mie-based intensity distribution at the \textit{'Stage~3'} (see
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Fig.~\ref{time-evolution}). The EHP density is still relatively small to affect
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the EHP evolution or for diffusion, but is already high enough to
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change the local optical properties. Below the magnetic dipole
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@@ -612,7 +614,7 @@ license.
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induced transient optical response and the effect of newly formed
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EHP. This way, the distribution becomes more homogeneous and the
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effect is likely to be enhanced by electron diffusion inside Si
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- NPs. We refer to these nonlinear phenomena as \textit{'Stage~$4$'}.
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+ NPs. We refer to these nonlinear phenomena as \textit{'Stage~4'}.
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It is worth noting that it is possible to achieve a formation of
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deeply subwavelength EHP regions due to high field localization. The
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