In-fiber integrated gas pressure sensor based on a hollow optical fiber with two cores

We demonstrate an in-fiber integrated highly-sensitive gas pressure sensor based on a special designed hollow eccentric twin-core optical fiber (HTCF). In this design, the core in the hole and the core in the annular cladding of the HTCF are separately used as sensing arm and reference arm. Then, in-fiber gas pressure detection can be first realized in the long hole of the HTCF. The experimental results show that the sensor exhibits a gas pressure sensitivity of 0.42 nm/bar, with low temperature sensitivity of −51 pm/℃, and a maximum bending sensitivity of 98 pm/μm. Comparing with traditional optical fiber gas pressure sensors, this device first realizes in-fiber gas pressure detecting through the special designed optical fiber with a compact size which can be easily connected and integrated in practical applications.