Optical Erasure and Reconfiguration of Surface‐Relief‐Gratings of Azo Polymer and Azo Molecular Glass: A Comparative Study on Soft‐Lithographic Duplicates

Abstract

Surface‐relief‐gratings (SRGs) of azo polymers and azo molecular glasses have attracted considerable interest for their erasable and reconfigurable characteristics. Herein, the optical erasure of soft‐lithographically duplicated SRGs of an azo polymer (BP‐AZ‐CN) and an azo molecular glass (IAC‐4) is investigated to tackle a long‐standing problem from “memory” effect existing in optically inscribed SRGs. The optical erasure is performed by single laser beam irradiation at wavelength of 488 nm with different polarizations, and the erasing behavior is thoroughly investigated by real‐time diffraction efficiency measurement and atomic force microscopy (AFM) observation. Showing no obvious dependence on the light polarizations, the optical erasure of IAC‐4 grating is a relatively fast process, and the original one can be completely erased and recreated. In contrast, the erasure of BP‐AZ‐CN grating is not only much slower, but also strongly correlated with the light polarizations. Upon the p‐polarized light irradiation, the grating profiles are substantially distorted during the erasure with a significant difference in that of the s‐polarized light irradiation. The gratings cannot be completely erased by the lights with all the polarizations. The erasure behavior is found to be determined by the effects of surface tension and mass transfer along the light polarization direction to different extents.

Keywords

• azo molecular glass
• azo polymers
• optical erasure
• soft-lithographic replication
• surface relief grating