High sensitivity stretched-abrupt-tapered Mach-Zehnder interferometer with optical attractive force for active microsensing applications

We demonstrate micro tapered fiber Mach-Zehnder interferometer with one of the two abrupt tapers is stretched and thinned to a diameter of 3.64 μm whereas the other one keeps its diameter of around 45 μm. The stretched and thinned abrupt taper can enlarge the optical path length difference between core and cladding modes to lead to a narrower free spectral range. The significantly exposed evanescent field can generate the optical attractive force to attract microparticles and can even substantially change the properties of external materials through photothermal effect when an optical power of up to 116 mW is launched.