Del Villar, IgnacioMatías Maestro, IgnacioArregui San Martín, Francisco Javier2018-04-052018-04-0520060306-8919 (Print)1572-817X (Electronic)10.1007/s11082-006-9002-3https://academica-e.unavarra.es/handle/2454/28214This is a post-peer-review, pre-copyedit version of an article published in [insert journal title]. The final authenticated version is available online at: http://dx.doi.org/0.1007/s11082-006-9002-3The sensitivity of Long-period fiber gratings (LPFGs), coated with high-refractive-index thin film overlays, to the refractive index and the thickness of the overlay, and to the ambient refractive index, can be enhanced with a design based on a two-overlay coating of an LPFG. The first overlay of lower refractive index than the cladding affects the guidance of a cladding mode in the second overlay of higher refractive index than the cladding. This causes a more abrupt cladding modal redistribution than with the deposition of a unique high-refractive-index overlay. The phenomenon is analyzed with a method based on a vectorial analysis of modes and the application of coupled mode theory.application/pdfeng© Springer 2006GratingsCoupled-mode analysisThin filmsOptical fiber sensorsinfo:eu-repo/semantics/articleinfo:eu-repo/semantics/openAccess