Temperature Sensor in Suspended Core Hollow Fiber Covered With Reduced Graphene Oxide

A compact temperature sensor based on a Mach-Zehnder interferometer (MZI) is demonstrated in a suspended core hollow fiber (SCHF) covered with reduced graphene oxide (rGO). The MZI is constructed by connecting two single-mode fibers with an intermediate section SCHF in offset splicing, which introduces the interference between the fundamental and high-order modes of the suspended core. The SCHF-based MZI without rGO is insensitive to the temperature; however, after employing rGO into the SCHF, the temperature sensitivity of ~179.4 pm/°C in the range of 30 °C-80 °C is obtained experimentally. Compared to microfiber-based sensors, the annular cladding can prevent the sensor from external environmental pollution. The proposed rGO-based all-fiber temperature sensor has good mechanical strength and is well compatible with fiber-optic systems, which makes it a good candidate for temperature monitoring. Meanwhile, the air hole of the SCHF is convenient for forming microfluidic channel to realize gas concentration or humidity sensing.