(Optical Society of America, 2005) Del Villar, Ignacio; Achaerandio Alvira, Miguel; Matías Maestro, Ignacio; Arregui San Martín, Francisco Javier; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Gobierno de Navarra / Nafarroako Gobernua
It was proved that the deposition of an overlay material onto a long-period fiber grating causes important
shifts in the wavelengths of the typical attenuation bands that are caused by coupling between cladding and
core modes [Opt. Lett. 27, 682 (2002)]. A theoretical model for analyzing a multilayer cylindrical waveguide
is presented that permits the phenomenon to be understood and predicted. An overlay of higher refractive
index than the cladding starts to guide a mode if a certain thickness value is exceeded. This causes large
shifts in the resonance wavelength induced by the grating. One important application of this phenomenon to
sensors is enhancement of the sensitivity of a long-period fiber grating to ambient conditions. Theoretical
results are corroborated with experimental ones obtained by electrostatic self-assembly.
