During the last decades,much research has been done in the field of fiber optic sensing technology and more concretely in thin films coated optical fiber sensors.The deposition of thin-films on optical fibre substrates has permitted,during the last decade,widening the traditional domains of application of optical fibre sensors(e.g.,gyroscopes,strain and temperature)to other research fields.These thin films could be built up onto diverse types of fibers and optical architectures.And this is possible thanks to modern deposition techniques,which permit coating the optical fibre with materials,whose properties change as a function of a biological or chemical species.Most of the times,those materials enable the introduction of losses to the propagation of light in the optical waveguide.And those losses get modulated as a function of the target parameter.One particular type of thin films coated optical fiber sensors are those based on Lossy Mode Resonances(LMR),developed by the first time in our laboratories.