Holographic multiplexing in a photopolymerisable hybrid sol-gel

Holographic multiplexing techniques enhance functionality and information storage by leveraging the inherent selectivity of holograms. This is crucial for advancing holographic sensors, which excel in simultaneously detecting multiple parameters from a single input signal. This study explores the potential of the recent photopolymerisable hybrid sol-gel (PHSG) material for application in Space sensing systems through the investigation of its holographic angular multiplexing capabilities. For the first time, to the best of our knowledge, we report the successful recording of up to five angularly multiplexed gratings with diffraction efficiencies (DE) ≥ 15% in 187 ± 18 µm PHSG layers. A 3 mW/cm² laser beam was used to record gratings (0–20° angular separation) with a spatial frequency of 800 ± 20 lines/mm utilising different exposure times. The study revealed that each successive multiplexing in the single-layer region resulted in a decrease in the material’s recording sensitivity. Holographic recording sensitivity and DE growth during the grating formation period depend on the number of gratings multiplexed in the layer. The seven-month-old, multiplexed gratings demonstrate consistent DE, stable angular selectivity and diffraction angle. This study positions the PHSG material as a promising candidate for developing reliable multiplexed devices.