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In the first experiment, illustrated by Figure \ref{Figure1}, we used a Q-switch Nd:YAG laser (EverGreen 200, Quantel, Les Ulis, France), which produced a pulse of energy $E$ = 200 mJ at a central wavelength of 532 nm during 10 ns in a 5 mm diameter circular beam of 5 mm diameter (so that section $S$=20 mm$^2$). We defined Z as the laser beam axis and the laser impact location on the medium as the origin of coordinates (0,0,0). The laser beam was absorbed in a 4x8x8 cm$^3$ tissue-mimicking black mat phantom made of water and of 5\% polyvinyl alcohol, 1 \% black graphite powder and 1\% salt. A freezing/thawing cycle was applied to stiffen the material to a value of 15$\pm$5 kPa \cite{17375819}. The laser is absorbed in the medium with an exponential decay of the optical intensity $I(z)=I_0 \exp(- \gamma z)$ along medium depth $z$, where $I_0=\frac{1}{S}\frac{d E}{dt}$ is the incident intensity distribution at the surface (the reflection on the black mat material being neglected) and $\gamma$ the absorption coefficient of the medium.  The absorption coefficient $\gamma$ can be estimated by calculating the skin depth $\delta = (\pi \sigma \mu_r \mu_0 \nu)^{\frac{1}{2}$, \nu)^{\frac{1}{2}}$,  where $\sigma$ is the electrical conductivity of the medium, $\mu_r \mu_0$ its permeability and $\nu$ the frequency of the radiation. Substituting $\sigma$ = 1 S.m$^{-1}$, $\mu_r \mu_0 \approx 4 \pi \times 10^{-7} H.m^{-1}$ and $\nu = 532 nm$, the skin depth for our medium is about 47 $\mu$m. We have validated experimentally this value by measuring the fraction of light which go through different thicknesses of the medium (respectively 0, 30, 50 and 100 $\mu$m) with a laser beam power measurement device (QE50LP-S-MB-D0 energy detector, Gentec, Qu\'e bec, QC, Canada). We found respective power of 100\%, 88\%, 71\% and 57\%. An exponential fit indicated that $\gamma^{-1} \approx$ 50 $\mu m$ in our sample, meaning that 63\% of the radiation is absorbed in the first 50 micrometers of the sample. The absorption of the laser beam by the medium gives then rise to an absorbed optical energy $q = \gamma I$. Assuming that all the optical energy is converted to heat, a local increase of temperature appears. Temperature distribution $T$ in absence of convection and of phase transition can be computed using the heat equation:  \begin{equation}