Vector displacement sensor based on femtosecond laser direct writing gratings and waveguides in a seven-core fiber

A novel vector displacement sensor based on femtosecond laser direct writing gratings and waveguides in a seven-core fiber was proposed. Avoiding the use of fan-in and fan-out devices, such a vector displacement sensor realized a highly integrated structure. The displacement sensitivity, displacement resolution and directional accuracy of the proposed sensor were 0.28 nm/mm, 0.01 mm, and <0.1°, respectively.