Highly sensitive pressure sensor based on cascaded long-period gratings

Pressure sensor based on cascaded long-period gratings (LPGs) is presented in this paper. Results obtained for a single LPG and for the cascaded structures are compared. For the cascaded LPGs we obtained very narrow and deep resonances, where wavelength shifts induced by pressure are easier to detect than when a single LPG is used as a sensor. It is shown that both cascaded and single LPGs offer similar high pressure sensitivities when the structures are written in a boron co-doped fiber and have the same grating period.