We report the experimental investigation of the sensitivity characteristics to the surrounding refractive index (SRI) in thinned long period gratings (LPGs) for a wide range of fiber diameters and different low-orders cladding modes. Wet chemical etching combined with microscopic and spectral analysis allow us to experimentally retrieve the SRI sensitivity characteristics of thinned LPGs. The obtained results allow us to identify accurately the dependence of the sensitivity characteristics on the fiber radius, taking into account the SRI range and the order mode. This provides a useful tool to identify the thinned structure able to fulfill the sensitivity requirements by maintaining an acceptable robustness level.
© 2007 Optical Society of America
Fiber Optics and Optical Communications
Original Manuscript: March 28, 2007
Revised Manuscript: July 23, 2007
Manuscript Accepted: August 4, 2007
Published: September 24, 2007
Agostino Iadicicco, Stefania Campopiano, Michele Giordano, and Andrea Cusano, "Spectral behavior in thinned long period gratings: effects of fiber diameter on refractive index sensitivity," Appl. Opt. 46, 6945-6952 (2007)