All-Optical Patterning of Azo Polymer Films
Yager, K.G.; Barrett, C.J. "All-Optical Patterning of Azo Polymer Films" Current Opinion in Solid State and Materials Science 2001
This review describes the experimental observations that have been made with regard to azo surface patterning. The azo-polymer patterning phenomenon was discovered in 1995, and has spawned a significant number of research papers. Considerable progress has been made, yet the exact nature of the molecular mechanism has not yet been resolved. This paper thus discusses the various results and offers perspectives on future experiments that could advance the field.
Thin films of polymers containing non-linear optical chromophores based on azobenzene have been shown to respond mechanically to low power light interference, resulting in a transfer of an arbitrary optical pattern to surface relief in a single step, often well below the usual glass transition temperature. The timescale for this process is seconds to minutes, and the resulting surface relief patterns can display a depth of features similar to that of the original film thickness. A series of mechanisms has been proposed to describe the origin of this effect, but none are currently able to rationalize the diverse set of surface patterns observed to be formed with various combinations of circularly and linearly polarized inscription lasers.