Novel in-line fiber-optic Fabry-Perot sensors based on etched Erbium- and Boron-doped optical fibers

Novel in-line fiber-optic extrinsic Fabry-Perot interferometers (EFPIs), with cavity lengths of up to ∼9µm, are fabricated by chemically etching the Erbium- and Boron-doped optical fibers and splicing the etched optical fiber to a single-mode fiber, respectively. The strain and temperature responses of the EFPI sensors are investigated by experiments. Both good linearity and high sensitivity are achieved. Such types of EFPI sensors are very cost-effective and suitable for mass production, offering great potentials for wide applications where the sensor cost is essential.