Integrated Raman spectroscopic sensor based on silicon nanowire waveguides

In this article we propose a novel Raman spectroscopic sensor which employs silicon nanowire waveguides for excitation and collection of Raman signal, and an integrated micro-ring resonator as a filter. Preliminary experimental results show that the extinction ratio of the filter including the ring resonator together with the grating coupler is more than 60 dB and the total insertion loss from the laser to the detector is less than 10dB. Theoretical calculations indicate that this high stray light rejection of the filter allows the observation of Raman signal at frequency as low as 4 cm-1 . By employing the evanescent field of the silicon waveguide as excitation and collection of Raman signal, along with the integration of the filter and potentially a tunable semiconductor laser and the detector, a miniaturized Raman spectroscopic sensor can be realized on SOI platform