Optochemical Organization
in a Spatially Modulated
Incandescent Field: A Single-Step Route to Black and Bright Polymer
Lattices
- Publication date
- 2013
- Publisher
Abstract
We report that incandescent beams patterned with amplitude
depressions
(dips) suffer instability in a photopolymerizable system and organize
into lattices of black and bright self-trapped beams propagating respectively,
through self-induced black and bright waveguides. Such optochemically
organized lattices emerge when beams embedded with a hexagonal or
square array of dips initiate free-radical polymerization and corresponding
changes in refractive index (Ξ<i>n</i>) along their
propagation paths. Under these nonlinear conditions, the dips evolve
into a hexagonal or square lattice of black beams, while their bright
interstitial regions become unstable and divide spontaneously into
multiple filaments of light. These filaments have a characteristic
diameter (<i>d</i><sub>f</sub>) and organize into a variety
of geometries, which are determined by the shape and dimensions of
the bright interstices. At interstitial widths > 2<i>d</i><sub>f</sub>, filaments are randomly positioned in space, whereas
at widths < 2<i>d</i><sub>f</sub>, the interstices are
occupied by a single file of filaments encircling each dark channel.
When the interstitial width β <i>d</i><sub>f</sub>, the filaments organize into lattices with long-range hexagonal
or square symmetry. By employing anisotropic interstices such as rectangles,
filamentation can be selectively elicited along the long axis, leading
to a lattice of filament doublets. This work demonstrates the versatility
and significant potential of optochemical organization to generate
complex, optically functional polymer lattices, which cannot be constructed
through conventional lithography or self-assembly. Specifically, the
study introduces a new generation of waveguide lattices, in which
light propagation is co-operatively managed by black and bright waveguides;
the former suppress local light propagation and, in this way, enhance
light confinement and guidance in proximal bright waveguides