LAUSR

By introducing the sub-wavelength grating (SWG) waveguide in the long-range surface phonon resonance (LRSPhR) device, a mid-infrared Fano resonance is formed due to the coupling between surface phonon polariton and Bloch mode. By taking advantage of strong light-matter interaction in the SWG, such Fano resonance is expected to offer improved sensing performance. Based on the rigorous coupled-wave analysis (RCWA) method, the index sensitivity and figure of merit of such a sensor reach 7496 RIU −1 and 46,432, respectively, which is 6 times compared with the conventional waveguide-coupled LRSPhR. The proposed SWG-coupled Fano resonance can be a promising platform for mid-infrared biochemical sensing.