Optical Supercavitation in Soft Matter

We investigate theoretically, numerically, and experimentally nonlinear optical waves in an absorbing out-of-equilibrium colloidal material at the gelification transition. At a sufficiently high optical intensity, absorption is frustrated and light propagates into the medium. The process is mediated by the formation of a matter-shock wave due to optically induced thermodiffusion and largely resembles the mechanism of hydrodynamical supercavitation, as it is accompanied by a dynamic phase-transition region between the beam and the absorbing material.

Figure 1

The initial stage of the formation of the cavitation. The thick line is material density ($\zeta =0$, $\xi >0$); the thin line is temperature. Quantities are scaled to their peak value ($\alpha =6$, $\delta =1$, $s=10$, $\eta =0.1$, ${\rho }_0=1$, and $\widehat{A}=0.1$).

Figure 2

Density distribution $\rho$ (depletion layer) at different instants. The parameters are as in Fig. 1.

Figure 3

Temperature-driven (thin line) shock front in the longitudinal ($\xi =0$) and transverse ($\zeta =0$) sections (the thick line is density). The parameters are as in Fig. 1.

Figure 4

Self-transparency mediated by the shock front. Top: Beam intensity. Bottom: Fluorescence signal $\rho |\psi {|}^2$. The parameters are as in Fig. 1.

Figure 5

Experimentally retrieved fluorescence signal due to the formation of a propagating beam in the material at three different instants. The inset shows a three-dimensional representation at $t=100\mathrm{s}$ (arbitrary scale).