Circularly polarized lights illumination to fabricate helical surface relief in azo-polymer film

An organic azo-polymer [1], exhibiting surface relief formation arising from light-induced mass transport through cis-trans photo-isomerization, has been investigated for a variety of applications; this includes optical integrated circuits and holographic data storages. In general, the mass transport driving force acts along a gradient of the optical spatial intensity profile, and it is thus difficult to structure a helical surface relief in azo-polymer film. To-date, we and co-workers have reported that an optical vortex with orbital angular momentum can twist an azo-polymer to fabricate a helical surface relief arising from wavefront-sensitive mass transport [2, 3]. The spin angular momentum associated with a helical electric field also forces micro-particles to spin; however, there are no reports concerning helical surface relief formation due to spin angular momentum transfer effects [4].