Ultrahigh Sensitivity Mach-Zehnder Interferometer Sensor Based on a Weak One-Dimensional Field Confinement Silica Waveguide.

We report a novel Mach-Zehnder interferometer (MZI) sensor that utilizes a weak one-dimensional field confinement silica waveguide (WCSW). The WCSW has a large horizontal and vertical aspect ratio and low refractive index difference, which features easy preparation and a large evanescent field for achieving high waveguide sensitivity. We experimentally achieved WCSW ultrahigh waveguide sensitivity of 0.94, MZI sensitivity of 44,364 π/RIU and a low limit of detection (LOD) of 6.1 × 10-7 RIU.