Optimization of a guided-mode resonance filter by varying the thickness of the buffer layer

In this Letter, we demonstrate that by adjusting the thickness of the buffer layer, the optical responses of a guided-mode resonance filter (GMRF) can be improved for sensor applications. The GMRF is fabricated using a replica molding with a plastic substrate and a UV-curable polymer. SiO₂ buffer layers of different thicknesses are deposited before the waveguide-layer deposition. The sensitivity of the GMRFs decreases slightly with increasing SiO₂ layer thickness. By contrast, the full width at half-maximum reduces substantially with increasing SiO₂ layer thickness, resulting in the improvement of the overall figure of merit.