Distributed Fiber Optic Measurements of Strain and Temperature in Long-Span Composite Floor Beams with Simple Shear Connections Subject to Compartment Fires.

This study explores an instrumentation strategy using distributed fiber optic sensors to measure strain and temperature through the concrete volume in large-scale structures. Single-mode optical fibers were deployed in three 12.8 m long steel and concrete composite floor specimens tested under mechanical or combined mechanical and fire loading.

Micrometer-accuracy 2D displacement interferometer with plasmonic metasurface resonators.

In this Letter, a high-accuracy, two-dimensional displacement sensor is proposed, designed, and demonstrated based on the concept of an extrinsic Fabry-Perot Interferometer. The sensor is composed of two bundled single-mode optic fibers in parallel and two plasmonic metasurface resonators inscribed on a gold substrate via a focused ion beam. The fiber end surface and the metasurface are in parallel with a small cavity between.