Grating Substrates Fabricated by Nanoimprint Lithography for Fluorescence Microscopy

Abstract

In this study, plastic grating substrates with subwavelength period were fabricated by nanoimprint lithography (NIL) and applied for the measurements of grating coupled-surface plasmon resonance (GC-SPR) field-enhanced fluorescence and fluorescence microscopic observation. Thermal and UV NIL were used for the fabrication of gratings. The grating fabricated by the latter process exhibited superior plasmon coupling characteristics to the former. The result of fluorescence detection indicated that the difference between the two structures fabricated by thermal and UV NIL affected the enhancement of fluorescence. Furthermore, the grating substrate with 39 nm groove depth fabricated by UV NIL produced an SPR dip, and it was found that the SPR of this grating substrate was dependent on duty ratio. The results of rigorous coupled wave analysis (RCWA) supported the experimental results well. The appropriate duty ratio of the grating fabricated by UV NIL with 39 nm groove depth was 0.6 to 0.8.