Holographic photo-morphing of polymer surfaces for reprogrammable diffractive optics

The fabrication of reconfigurable diffractive optics requires lithographic techniques capable of dynamically modifying surface geometries. Traditional methods, such as etching and resist-based processes, impose limitations on post-fabrication modifications, increasing manufacturing complexity and cost. Holographic photomorphing of azopolymer surfaces enables direct, all-optical, and reversible fabrication of diffractive optical elements. In this study, we demonstrate the fabrication of linearly chirped diffraction gratings using computer-generated holography to project structured illumination onto azopolymer films. The digital lithographic setup allows precise control of the intensity patterns, enabling the fabrication of chirped gratings with continuously varying periodicity. Real-time diffraction analysis is performed using a probe beam to capture the evolution of surface modulation and diffraction efficiency during the writing process. Experimental results confirm theoretical predictions, with diffraction efficiencies up to 34%. The ability to fabricate complex diffractive elements without sequential exposures or mechanical alignment enhances the versatility of this method and provides a scalable approach for tunable optical components.