Theoretical and Experimental Analysis of the Sensitivity of Guided Mode Resonance Sensors

The aim of this work is to design highly sensitive guided mode resonance (GMR) sensors for the visible spectral range providing maximum spectral shift of the resonance leaky mode with a change of the refractive index. The GMR sensor consists of a fused silica linear grating coated with dielectric materials by atomic layer deposition (ALD). Discrete layers of titanium oxide deposited by ALD served as model analyte systems. Rigorous coupled wave analysis (RCWA) calculations of model systems identified the optimal aspect ratio of the linear grating. Polarized transmittance measurements are in excellent agreement with the theoretical data. The optical response of the GMR sensor to a 21 nm TiO2 film amounts to a 76−87 nm shift of several narrow bands providing high optical sensitivity for ultrathin films. Sensitivity tests in a fluidic environment were also performed. The calculated optical response of an optimized GMR grating for a change of the refractive index unit (RIU) of the resonance cavity (Δλ/Δnc) is ...