Phase separation and pattern instability of laser-induced polymerization in liquid-crystal-monomer mixtures

Directly written by a ultra-short femto-second laser pulse, we report the phase separation and pattern formation induced by polymerization in a liquid-crystal-monomer mixture. By varying the scanning speed of optical fields along a line, pattern transitions of photon-induced polymer structures are illustrated in shapes of double-humped, single-humped, and broken stripes. The experimental data collected by optical microscopic images are in a good agreement with numerical simulations based on a modified set of coupled 2 + 1 dimensional diffusion equations. The demonstration in this work provides a step for controlling phase separation morphologies as well as transferring patterns in polymer-dispersed liquid crystals. (C) 2011 Optical Society of America