Spontaneous formation of 3-D optical and structural lattices from two orthogonal and mutually incoherent beams of white light propagating in a photopolymerisable material

The spontaneous generation of 3-D lattices by an orthogonal pair of white light beams propagating in a polymerisable organosiloxane medium is described. Lattice formation occurs through polymerisation-induced modulation instability of the beams, each of which spontaneously divides into multiple self-trapped filaments. Dynamic interactions between the beams lead to a 3-D lattice with near-cubic symmetry, where each lattice point corresponds to the intersection of an orthogonal pair of filaments. Three different lattice types were found. Each leaves an indelible imprint in the photopolymer, which transforms from an isotropic and homogeneous medium into a 3-D microperiodic lattice constructed entirely of intersecting cylindrical waveguides.