Light induced conch-shaped relief in an azo-polymer film

We have discovered that a novel chiral structured surface relief (termed 'conch'-shaped surface relief) with a height of over 1 μm can be formed in an azo-polymer film merely by employing circularly polarized optical vortex irradiation with a total angular momentum of j = ±2. The temporal evolution of the conch-shaped surface relief in the azo-polymer film was also observed. The results provide physical insight into how the angular momentum of light is transferred to a material through mass transport by cis-trans photo-isomerization. Such conch-shaped surface reliefs with chirality, in which functional chemical composites can be doped, enable new applications, such as planar chiral metamaterials, plasmonic holograms, and identification of chiral chemical composites.