Optical frequency comb based system for photonic refractive index sensor interrogation.

In this contribution, we demonstrate how an optical frequency comb can be used to enhance the functionality of an integrated photonic biosensor platform. We show that if an optical frequency comb is used to sample the spectral response of a Mach-Zehnder interferometer and if the line spacing is arranged to sample the periodic response at 120° intervals, then it is possible to combine these samples into a single measurement of the interferometer phase. This phase measurement approach is accurate, independent of the bias of the interferometer and robust against intensity fluctuations that are common to each of the comb lines. We demonstrate this approach with a simple silicon photonic interferometric refractive index sensor and show that the benefits of our approach can be obtained without degrading the lower limit of detection of 3.70×10 RIU.