Effect of induced inner curvature on refractive index sensitivity in internally tilted long-period gratings

A new complete analysis of the effect of induced inner curvature on refractive index (RI) sensitivity in internally tilted long-period gratings (ITLPGs) is presented. The responses in terms of RI sensitivity of a standard LPG and different ITLPGs with curvature values between 15 and 19  m^-1 were compared. The analysis suggests first, that the larger the induced curvature, the greater the RI sensitivity; and second, that the RI sensitivity exponentially increases with both the curvature and cladding mode order. RI sensitivity greater than 100 nm RIU^-1 can be attained with curvature greater than 25  m^-1 for LP₀₆ mode. Conversely, the temperature sensitivity of ITLPGs is comparable to standard LPGs for the considered cladding mode order.