Optical Spatial Solitons in Soft Matter

We predict that spatial self-trapping of light can occur in soft matter encompassing a wide class of new materials such as colloids, foams, gels, fractal aggregates, etc. We develop a general nonlocal theory that allows one to relate the properties of the trapped state of Maxwell equations to the measurable static structure factor of the specific material. We give numerical evidence for stable trapping in fractal aggregates and suggest also the possibility of soliton spectroscopy of soft matter.

Figure 1

(a) Normalized peak intensity $\max (u^2)$ vs the normalized beamwidth (i.e., the standard deviation of $u^2$), obtained from Eqs. (7, 8) coupled to Eq. (13) for various fractal dimensions $D$. (b) Normalized beam waist and power vs the fractal dimension $D$ for $\beta =2$.

Figure 2

As in Fig. 1, soliton normalized peak intensity (a) and power (b) vs normalized waist for the paraxial ($ϵ=0$) and nonparaxial ($ϵ=0.1$) model ($D=2.5$, $\xi =100r_s$, $\kappa =0.1$).

Figure 3

Propagation (symmetrized for $r<0$) of an input Gaussian beam $u(\zeta =0,r)=A\exp (-{\sigma }^2)$ in the paraxial regime ($ϵ=0$), (a) $A=0.0055$ and (b) $A=0.006$, and beyond the paraxial regime ($ϵ=0.01$), (c) $A=0.0055$ and (d) $A=0.006$. Stable trapping when $ϵ=0$ is achieved for $A=0.0052$ ($D=2.5$, $\kappa =0.1$, $\xi =100r_s$).