Manifestation of an ultra-high sensitive fiber optic microbend sensor realized by shining a Bessel-Gauss beam

摘要

Bend-induced loss in microbending fiber-optic sensor has proved to be an effective one for the direct and indirect measurement of various physical parameters. In this research, a novel and highly sensitive microbend sensor has been explored by launching a zero order Bessel-Gauss beam inside a waveguide arrangement having a No-core fiber bonded amidst two special higher-order mode supporting fibers. By harnessing the special characteristics of the Bessel-Gauss beam, pairing of manifold high-order modes has been affirmed inside the sensor structure. The captivating feature of such sensor is that it defies the conventional wisdom and significantly improves the sensitivity without any intricate fabrication techniques like in tapering, bending etc. To our knowledge, such realization of Bessel-Gauss beam-shined microbend sensor has not been reported earlier in any of the contemporary literature. In support of our theoretical analysis; a Beam propagation method is employed in OptiBPM software (Optiwave Systems Inc.) to envisage the full transmission spectrum of the waveguide. For different bend radii, the sensor response has been numerically investigated and it is anticipated that the sensitivity is expected to be enhanced by a gentle reduction in the bend radius. With the presence of six microbends, the proposed sensor manifests an average bend sensitivity of 2.8 dB/mm which is 3.2 times superior to the classical microbend sensing configuration. Due to such superior sensing performance, the present paradigm paves the way for many potential applications, like damage detection of various engineering structures, and measurement of different physical parameters like temperature and pressure.