Azobenzene Thin Film Meta-Couplers Based on Stacked Parallel-Superimposed Gratings

Meta-couplers capable of engineered spectral responses are increasingly important for photonic and sensing applications. Laser interference lithography was used to fabricate metasurface couplers (meta-couplers) by sequentially superimposing parallel surface relief gratings onto azobenzene thin films. Up to nine parallel superimposed gratings were successfully inscribed within the same physical region while retaining the optical and structural properties of each consecutive inscription. The resulting meta-couplers produced tailored spectral fingerprints across the visible and near-infrared, demonstrating a scalable platform for passive optical signature enhancement, wavelength-selective filtering, and compact photonic devices.