Gold-induced photothermal background in on-chip surface enhanced stimulated Raman spectroscopy

Surface enhanced Raman spectroscopy (SERS) and stimu- lated Raman spectroscopy (SRS) are well established techniques capable of boosting the strength of Raman scattering. The combination of both techniques (surface enhanced stimulated Raman spectroscopy, or SE-SRS) has been reported using plasmonic nanoparticles. In parallel, waveguide enhanced Raman spectroscopy has been devel- oped using nanophotonic and nanoplasmonic waveguides. Here, we explore SE-SRS in nanoplasmonic waveguides. We demonstrate that a combined photothermal and thermo- optic effect in the gold material induces a strong background signal that limits the detection limit for the analyte. The experimental results are in line with theoretical estimates. We propose several methods to reduce or counteract this background.