(Springer, 2006) Del Villar, Ignacio; Matías Maestro, Ignacio; Arregui San Martín, Francisco Javier; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Gobierno de Navarra / Nafarroako Gobernua
The 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.