We study two photon absorption (TPA) induced surface relief formation in an azo-polymer thin film by illumination of picosecond near-infrared optical vortex pulses with the corresponding intensity of >5 GW/cm2 at the focal plane.
We discover, for the first time, that the optical vortex creates an unexpected flower-shaped surface relief with 3-8 petals along an azimuthal direction, corresponding to the topological charge of the incident optical vortex. This surface relief manifests the modulational instability associated with nonlinear light-matter interaction in the azo-polymer film.
We demonstrate the formation of chiral surface relief of azo-polymers by irradiation of picosecond 1-μm optical vortex with a pulse width of 8ps via two-photon absorption. Optical vortex induced TPA enables us to create the chiral surface structures only within an extremely narrow defocusing tolerance with high three-dimensional (longitudinal and transverse) spatial resolution beyond the diffraction limit and without undesired outer rings of Airy pattern.
We report on the first demonstration of picosecond optical vortex-induced chiral surface relief in an azo-polymer film due to two-photon absorption isomerization. The chiral surface relief exhibits an extremely narrow defocusing tolerance without undesired outer rings due to the Airy pattern of highly focused light. Such chiral surface relief reflects a z-polarized electric field with an azimuthal helical phase caused by spin–orbital angular momentum coupling.