Silicon Photonic Wire Waveguide Sensors

Silicon photonic wire evanescent field (PWEF) waveguide sensors have a very high intrinsic response to molecular adsorption. This response arises from the high refractive index contrast and small size of these waveguides, which in combination cause much of the electric field to be localized to a thin layer adjacent to the waveguide surface. We describe the basic theory of PWEF waveguide sensors and compare the predicted PWEF sensor performance with that of surface plasmon resonance (SPR) and other waveguide systems. Finally, we present experimental results for PWEF sensors incorporated into integrated optical circuits employing Mach–Zehnder interferometers (MZIs), ring resonators, and folded waveguide structures that both amplify and facilitate the interrogation of the PWEF sensor response.