Tightly focused optical skyrmions induced relief structures through two-photon absorption

Optical skyrmions exhibit a spatially invariant (topologically protected) polarization texture during beam propagation even under turbulence. Azo-polymers exhibit a unique photo-induced mass transport with polarization and intensity sensitivities under visible light illumination. The resulting surface reliefs of azo-polymers enable the direct observation of the light–matter interactions with optical skyrmions. In recent years, we have discovered that the visible optical skyrmions direct azopolymers to form a twisted crescent-shaped relief. Tightly focused optical skyrmions offer spin and orbital angular momentum coupling effects. Furthermore, nonlinear optical processes, such as two-photon absorption, under tightly focusing conditions provide exotic light–matter interactions beyond the conventional single-photon absorption process. We herein report on the first demonstration of the two-photon absorption induced surface reliefs of azo-polymers with the tightly focused near-infrared optical skyrmions. The fabricated surface reliefs reflect directly the polarization structures of irradiated optical skyrmions.