Surface plasmon polariton coupling induced transmission of subwavelength metallic grating with waveguide layer

In this paper, we present the nanofabrication of a potentially coupled waveguide–surface plasmon resonance biosensor (CWSPRBs) by nanoimprint lithography. Subwavelength metallic gratings (SWMGs) with the pitches of 300 and 500 nm were fabricated by direct imprinting on PMMA layer which subsequently covered with a layer of Au. The key issue in this device is the coupling of surface plasmon with waveguide modes, which has been carefully investigated by measuring the coupling induced enhancement of light transmission. Both our measurement and simulation results indicate that the resonant coupling does exist for both 300 and 500 nm pitched gratings. This proves that the developed nanoimprint lithography is applicable for the CWSPRBs sensors which has significant advantages over traditional ones with a prism.