Reflection configuration of long-period grating sensor working at dispersion turning point

In this work discuss an application of chemical method, i.e., Tollen's reagent, for mirror fabrication on the end-face of the fiber with induced long-period grating (LPG). This simple and versatile technique can be used for thin silver layer deposition and formation of stable and well-reflecting mirrors for fiber-based devices. We have found that the LPG-based sensors working in reflective configuration at dispersion turning point (DTP) of higher order cladding modes allow for refractive index (RI) measurements with sensitivity reaching 4.429 nm/RIU. Such structures, after their proper biofunctionalization process, can be used as probes for label-free biosensing.