Fluorescence microscopic imaging using a substrate with a sub-wavelength grating

A study was conducted to demonstrate fluorescent microscopic imaging using a substrate with a sub-wavelength grating. Enhanced fluorescence detection was carried out using grating-coupled (GC)-surface plasmon resonance (SPR) to overcome the challenges associated with conventional prism coupled SPR-design. A thin metal coated grating substrate with a rectangular or trapezoidal surface profile in GC-SPR allowed the resonance angle to be reduced. The periodic structure was fabricated using two-beam interference and dry etching or UV-nanoprint lithography. It was also demonstrated that a periodical structure of 400 nm created on the substrate surface was covered with Ag and SiO ₂ layers to be used as a chip.