Accurate Morphology-Related Diffraction Behavior of Light-Induced Surface Relief Gratings on Azopolymers

Holographic relief gratings can be fabricated directly on the surface of azobenzene-containing materials (orsimplyazomaterials) without additional development steps.Despite often being described to have ideal sinusoidal profiles,the developing surface morphology in large amplitude gratingscan affect the light distribution of the writing interferogram,causing profile deformations and deviations in the expecteddiffraction behavior. In this work, we characterize the temporalevolution of the surface relief grating (SRG) morphologyfabricated by means of interference lithography on azopolymerfilms, quantitatively relating the results of a Fourier analysis oftheir surface profiles to the accurate measurement of efficienciesin the transmitted diffraction orders. A reliable surfacestructuration dynamics is empirically extracted from the analysis and used to formulate a simple but detailed diffractionmodel that, within the scalar diffraction theory, exhaustively describes the diffraction behavior of real SRGs without the needof complex rigorous electromagnetic theories. Our results add a deeper insight in the quantitative description of themorphology and the diffraction behavior of SRGs, which can contribute to their adoption for operating high-performance,reconfigurable, compact, and lightweight diffractive optical devices

Automated summary

This study characterizes the temporal evolution of surface relief gratings (SRGs) fabricated using interference lithography, and proposes a simple yet detailed diffraction model to accurately describe the diffraction behavior of SRGs. By conducting Fourier analysis of surface profiles, a reliable surface structuration dynamics is empirically extracted, providing insights for improving the performance and application of SRGs.