Fabrication of Surface Relief Micro‐Gratings in Azobenzene Films and Their Conversion to Gold Microwires

ABSTRACT A simple maskless method was used to produce large‐area surface relief micro‐gratings on azobenzene molecular glass films. A custom‐built bi‐facial pyramidal prism was used to split a 532‐nm laser beam into two, generating a sinusoidal interference pattern that induced photo‐driven molecular migration within a solid‐state azobenzene thin film. This method enabled the fabrication of highly uniform sinusoidal gratings with an unprecedented pitch of ∼64.5 µm, with an average modulation depth of ∼100 nm. Through selective chemical dissolution of unexposed areas of the film, followed by gold sputtering and lift‐off, the micro‐sized surface reliefs were converted into a well‐defined array of gold microwires. Profilometry, scanning electron microscopy, and energy‐dispersive X‐ray spectroscopy analyses confirmed the surface periodicity, structural uniformity, and selective metal deposition. This fabrication method provides a scalable, alignment‐tolerant technique for creating customisable in‐plane photonic and electromagnetic components, such as wire‐grid polarisers and on‐chip micro‐antennas.