We have discovered that a novel chiral structured surface relief (termed 'conch'-shaped surface relief) with a height of over 1 mm can be formed in an azo-polymer film merely by employing circularly polarized optical vortex irradiation with a total angular momentum of j 5 62. 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.S urface relief holograms 1-3 on azo-polymer films have been widely investigated through mass transport owing to a driving force based on an optical gradient force, anisotropic photo-fluidity, and cis-trans photoisomerization 4-6 . They allow for unique optical devices, such as active waveguides 7 and photonic circuits, by the doping of functional chemical composites, such as laser dyes and metal (or semiconductor, magnetic) nanoparticles into the films.In general, the mass transport driving force acts to direct the azo-polymer from a bright fringe toward a dark fringe along the polarization direction of the light. Thus, a spiral surface relief formation in the azo-polymer film is mostly inhibited by the irradiation of linearly polarized light.An optical vortex, i.e. light with a helical wavefront due to an azimuthal phase singularity, exp(imw) (where m is an integer known as the topological charge), has been widely studied in a variety of fields, such as optical trapping and guiding [8][9][10] , optical telecommunications 11 , and a super resolution microscope 12,13 , because of its unique characteristics, such as its annular intensity profile and orbital angular momentum, mh 14-17 .Recently, Ambrosio et.al. demonstrated spiral surface relief (termed ''spiral relief'' in their work) formation produced through linearly polarized higher-order optical vortex irradiation 18 . Tightly focused higher-order optical vortices can create a spiral surface relief with a shallow depth (10 , 20 nm) through slight mass-transport along an azimuthal direction owing to interference between longitudinal and transverse optical fields. However, there are still no reports on a single-arm chiral surface relief with depth and height on the micro-scale formed in azo polymer films, so far.Circularly polarized light with a helical electric field exhibits spin angular momentum, sh. Thus, the circularly polarized optical vortex has a total angular momentum (the sum vector of the orbital and spin angular momenta), jh, associated with its helicities of both the wavefront and the polarization [19][20][21] . These angular momenta of light are evidenced by the orbital and spinning motions of trapped particles in optical tweezers.Recently, together with another co-worker, we first dem...
