Stimulated Raman spectroscopy of analytes evanescently probed by a silicon nitride photonic integrated waveguide

We report, to the best of our knowledge, the first demonstration of stimulated Raman spectroscopy enhanced by a nanophotonic integrated circuit. The Raman response of low-concentration dimethyl sulfoxide is evanescently probed via centimeter-long wire waveguides. A signal enhancement of close to five orders of magnitude, as compared to the case of on-chip spontaneous Raman scattering, is demonstrated. This significant enhancement factor allows for the use of continuous-wave lasers with milliwatt-level power and uncooled detectors and, therefore, sets the basis of future all-on-a-chip Raman spectrometers suitable for both gas and liquid detection.