Surface-enhanced Raman scattering using nanoporous gold on suspended silicon nitride waveguides

A hybrid integration of nanoporous gold with silicon nitride waveguide has been realized for surface-enhanced Raman spectroscopy (SERS) at 633-nm wavelength. The SERS signal is excited through 580-nm-thick T-shape suspended waveguides and collected through an objective lens. Raman spectra for different mesa width at either transverse electric (TE) or transverse magnetic (TM) mode are measured and compared. The localized surface plasmon resonance of the nanoporous gold can result in a waveguide and polarization-dependent SERS enhancement. The presented miniaturized SERS chips can work from visible to near-infrared wavelength and a wide application prospect could be expected.