In-line all-fibre Fabry-Perot interferometer high temperature sensor formed by large lateral offset splicing

A novel in-line all-fibre compact Fabry-Pérot interferometer (FPI) high temperature optical fibre tip sensor formed by fusion splicing two sections of singlemode fibres with a large intentional lateral offset is proposed and demonstrated, for the first time to the authorś knowledge. Simple fabrication steps include only cleaving and fusion splicing. Because no other processes are involved, the fabrication is easy, safe, and cost-effective. The sensor has been tested for high temperature measurements showing a sensitivity of 41́nm/́C with good linearity and repeatability, and is capable of operation at temperatures up to 1000́C. It is expected that such a miniature FPI could find wide applications in mechanics, aeronautics, chemical sensing and metallurgy.