SERS chip fabricated by the thermal effect in a double-metal-cladding waveguide.

Abstract

Different from ordinary planar waveguide structure, we designed a double-metal-cladding waveguide (DMCW) for easier light coupling into the guiding layer from free space. In contrast to evanescent waves in a surface plasmon polariton waveguide, an oscillating wave is generated in the guiding layer. and a similar Fabry-Perot (FP) cavity can be formed by the DMCW. In past work, the FP cavity excited by the DMCW was used to study the refractive index of light, while in this work, the FP cavity is used to excite the photothermal effect of the metal substrate. It is a good connection between light and heat. The photothermal effect is investigated to promote the galvanic replacement reaction in the substrate. Although the experiment process is destructive to the DMCW structure, a surface-enhanced Raman scattering (SERS) chip is prepared on the basis of the photothermal effect in the DMCW. It shows that the DMCW can convert the energy of incident light into thermal energy, and then prepare the SERS chip. The chip has better uniformity, stronger activity, and higher sensitivity. The results demonstrate that the morphology of the SERS substrate created via the DMCW is far more elaborate than that via the surface plasmon polariton waveguide.