All-optical fabrication of ellipsoidal caps on azobenzene functional polymers.

We have fabricated an azobenzene (azo) polymer microellipsoidal cap array of hexagonal symmetry with high-power laser ablation and subsequent single-beam-induced mass migration. High-power interference with polarization-controlled triple beams is utilized to inscribe a circular bump array directly on the surface of the azo polymer film. The produced circular cap array is exposed to the linearly polarized beam, and the caps are stretched along the polarization direction of the irradiating beam. A model of gradient force emerged by the interaction of the polarized beam and azo polymer is constructed to explain the mechanism of such polarization-induced microscale shape deformation.