UV-based lithography and nano-imprint lithography for the fabrication of functionalized micro-nano sol-gel structures

A subwavelength structure incorporating a resonant waveguide grating embedded in a luminescent sol-gel layer enables a dual-color effect. The resonant waveguide grating consists of a diffraction grating and a high refractive index guiding layer, made of TiO2-based sol-gel with a refractive index (n_g = 2.2) which is higher than that of its TEOS/MTEOS sol-gel cladding (n_s = 1.45). This design is specifically engineered to achieve resonant reflection of TE-polarized incident waves in the visible green spectrum. The resonant structure is then coated with a thick layer of silicone doped with the luminescent material Y²O²S:Eu³⁺, which emits red light upon UV excitation. This quasi-symmetric structure remains transparent in the visible range, allowing the observation of the different phenomena. The grating is fabricated using both UV lithography and nanoimprint lithography on the sol-gel layer, showcasing the potential of these advanced techniques for producing precise microstructures. UV lithography enables high-resolution patterning, while nanoimprint lithography offers a low-cost, scalable fabrication method, making it ideal for replicating these microstructures on a larger scale for industrial applications. The sol-gel structure itself provides flexibility in the fabrication process, offering the advantage of being both cost-effective and highly customizable. Preliminary results will be presented at the conference, including the modeling and design of optimized microstructures. Experimental results featuring nanoimprinted sol-gel layers with resonant waveguide gratings and luminescent coatings will be shown. Optical measurements have been conducted to characterize the performance both the luminescent layer and the resonant grating. The obtained results will be analyzed and discussed.