Testing the diffusion hypothesis as a mechanism of self-healing in Disperse orange 11 doped in PMMA
This is an important piece of work that get's us one step closer to understanding self healing in dye-doped polymers, a phenomena that was discovered in our lab a decade ago. The first comment I always get when introducing our work at scientific meetings is that the laser is heating the material, causing the dye molecules to diffuse away from the beam. When the laser is turned off, the dye molecules diffuse back. So, rather than the molecules breaking apart and then reassembling themselves, they are just moving out then into the beam - a much less sexy phenomena.
The report of one of the reviewers summarizes our results best:
This manuscript describes a combined experimental and theoretical study on the recovery of absorption in dye-doped polymer samples exposed to high light intensities. There are several possible mechanisms for such a self-healing effect and it is of significant interest to understand which one(s) contribute. The paper presents a set of experimental data on the dynamics and spatial profile of the optical properties of the damage region. It then presents a thorough and detailed model of what is expected if diffusion of undamaged dye molecules into the damaged region is responsible for all or part of the recovery. The difference between the broadened profile of the concentration predicted by the diffusion model and the constant profile shape observed experimentally is persuasive in demonstrating that diffusion is not a significant contributor to the self-healing. The manuscript is well-presented, thorough, and sound. It warrants publication in JOSA B.
Congratulations to Shiva and Nathan for a job well done!