(IEEE, 2005) Del Villar, Ignacio; Matías Maestro, Ignacio; Arregui San Martín, Francisco Javier; Achaerandio Alvira, Miguel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Gobierno de Navarra / Nafarroako Gobernua
An overlay of higher refractive index than the
cladding is deposited on a Long Period Fiber Grating (LPFG).
This permits to improve in a great manner the sensitivity of the
device to ambient and overlay refractive index changes. This
causes large shifts of the attenuation bands in the transmission
spectrum. To obtain a maximum sensitivity for specific refractive
indices of the overlay and the ambient, an optimum overlay
thickness must be selected. If the refractive index of the overlay is
complex there is an additional phenomenon of vanishing of the
attenuation bands in the transmission spectrum. This occurs for
specific thickness values of the overlay. The problem is analyzed
with a numerical method based on LP mode approximation and
coupled mode theory. Experimental results are contrasted with
theoretical ones
