A single-mode fiber sensor based on core-offset inter-modal interferometer

A single-mode fiber (SMF) sensor based on core-offset inter-modal interferometer is demonstrated. Compared with the sensing head with the two core-offset joints, the improved sensor has a special advantage that the offset direction cannot significantly affect the extinction ratio (ER) of the transmission spectrum. So the improved sensor, which is made of SMF and a very short section of multimode fiber (MMF), appears repeatable and higher extinction ratio. And the refractive index (RI) sensitivity of −64.889 nm/RIU and temperature sensitivity of 73 pm/°C, respectively can be achieved. Its ease of fabrication makes it a low cost alternative to existing sensing applications.