Patterns of clouds in the sky, wind-sculpted striations in the desert sand, microstructures found on butterfly wings, spots and stripes of animal skin are examples of patterns that emerge spontaneously in nature. The physical laws that govern spontaneous pattern formation in these dissimilar systems are strikingly similar.
Our research examines such nonlinear phenomena when a system simultaneously undergoes optical and chemical changes. Because the optical and chemical properties of such systems can be precisely controlled, they provide convenient pathways to examine complex nonlinear processes. This research, while consistent with studies of nonlinear light propagation established by optical physicists and engineers, contributes new chemical perspectives to this field.
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Please see the video below for a general overview of the group's work.
Non-linear light forms
Nonlinear waves propagate without dissipating over long distances in space or time. They exist in spectacularly varied forms and dimensions, and play vital roles in processes such as excitations along polymer chains, chemical waves in reaction-diffusion systems, thermal solitons driving biochemical cycles, vibrations along proteins, pulses along nerves and within the heart, sound, ocean waves, clouds and space plasma.
We study nonlinear optical waves such as self-trapped beams and self-trapped filaments under the precise parameters of an optics experiment. The tremendous surge of creativity and progress in this field in the past 20 years is motivated in part by the promise of intelligent photonics without preconfigured circuitry; here the generation and interactions (e.g. fusion, fission, repulsion) of self-trapped beams are harnessed to manipulate and process light signals.
Regardless of whether light originates from the sun or a laser, a light beam will naturally broaden (diffract) while travelling through most transparent materials including air, glass and water. In certain types of materials however, the same beam triggers a transformation - such as a chemical reaction – that causes the refractive index along its path to increase.
A nonlinear situation arises in which the natural tendency of the beam to diffract is always opposed by refraction, which forces the beam to focus and self-trap.
Optochemical organization
We develop routes to 2-D, 3-D optical and microstructural lattices through mechanisms that marry the elegant spontaneity of self-organisation to the precision and directionality of directed-beam lithography. Unlike any other known self-organised structures, the resulting lattices are composed of multimode, polychromatic cylindrical polymer waveguides.
3D Printing Intelligent Coatings
3-D printing with nonlinear waves - this exploits the non-divergent nature of optochemical waves and shows that by embedding patterns within these waves, it is possible to print seamless 3-D objects both in dielectric and metallodielectric materials. This is challenging to achieve with current 3-D printers.
Functional materials
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By combining photochemistry and optics, we devise new strategies to address a principal goal of photonics research – to precisely control and manipulate light beams propagating in 3-D microstructures. Exploiting the properties and interactions of self-trapped light waves, we are also developing unconventional routes to three different applications. The first are Waveguide Encoded Lattices (WELs) - which like an insect’s compound eye - possess a significantly enhanced field of view. Fabricated by launching thousands of optochemical waves in a flexible, robust photopolymer medium, WEL lattices can serve as encapsulants of light-harvesting devices or light-shaping conformal coatings on LEDs.
Materials that compute with light
We examine how the soliton-like interactions of self-trapped waves within a photopolymer cube enable spontaneous transfer of binary information between light beams and create strategies for all-optical encoding and ultimately, computing.