Modification of the refractive index response of long period gratings using thinfilm overlays.

摘要

The response of a fibre optic long period grating (LPG) to the surroundingrefractive index is shown to be modified by the deposition of a thin film ofthickness of order 100 nm onto the cladding. The LPG becomes sensitive tosurrounding refractive indices greater than that of silica, and exhibits anenhanced sensitivity to external refractive indices lower than that of silica.