  We review an on-chip approach for spontaneous Raman spectroscopy and Surface
Enhanced Raman Spectroscopy (SERS) based on evanescent excitation of the
analyte as well as evanescent collection of the Raman signal using
Complementary Metal Oxide Semiconductor (CMOS) compatible single mode
waveguides. The signal is either directly collected from the analyte molecules
or via plasmonic nanoantennas integrated on top of the waveguides. Flexibility
in the design of the geometry of the waveguide, and/or the geometry of the
antennas, enables optimization of the collection efficiency. Furthermore the
sensor can be integrated with additional functionality (sources, detectors,
spectrometers) on the same chip. In this paper, the basic theoretical concepts
are introduced to identify the key design parameters and some proof-of-concept
experimental results are reviewed.
