Title:
Vectorial photopatterning of azopolymers for reprogrammable diffractive optics

Abstract:
Azobenzene-containing polymers provide a distinctive platform for surface lithography in which structured light directly writes, erases, and reshapes functional micro- and nanoscale reliefs. Their response originates from the reversible trans–cis photoisomerization of azobenzene molecules, which couples the local optical field to molecular reorientation, light-induced mechanical stress, and surface mass transport. Unlike conventional photoresists, this process does not require development, etching, or material removal and allows the same surface to be repeatedly reconfigured.

In this talk, I will present the general framework of vectorial photopatterning in azopolymers, showing how the intensity, polarization, wavelength, and temporal evolution of the writing field can become active lithographic design parameters. Starting from classical interference lithography, I will discuss the transition toward digitally programmable holographic schemes that involve computer-generated holography and  spatially resolved holographic polarization control. These approaches enable the direct fabrication of surface structures whose morphology reflects the full vectorial nature of the illuminating light.

I will then show how these capabilities can be exploited to realize reprogrammable diffractive optical elements, including gratings, multiplexed and chirped surfaces, diffractive lenses, microlens arrays, optical Fourier surfaces, and holographic projectors. Finally, I will discuss current routes toward predictive and scalable fabrication, including real-time optical metrology, feedback-controlled exposure, and the use of photopatterned azopolymer surfaces as reconfigurable masters for replication. This framework points toward a lithographic paradigm in which light becomes the only required tool for fabrication, optical functionality, and post-fabrication reprogramming.