No-core fiber surface plasmon resonance dual-channel sensor for refractive index and temperature sensing with compact structure

To improve the integration of sensors and meet the trend of miniaturization of devices, we propose and demonstrate a compact dual-channel surface plasmon resonance (SPR) fiber sensor for detecting refractive index (RI) and temperature. In this sensor, we chose the simplest structure of optical fiber: no-core fiber (NCF), as the sensing probe. Then the silver film was deposited on the NCF surface using magnetron sputtering to excite the SPR effect. Two sensing channels were constructed on the NCF, one channel deposited with silver film for RI detection, and another channel deposited with PDMS and silver film for temperature detection. Such a construction makes the sensor compact and small. The performance of the proposed sensor is studied theoretically and experimentally. The experiment shows that the maximum sensitivity of the sensor is 3039 nm/RIU and 3.53 nm/°C when the RI ranges from 1.333 to 1.375 and the temperature ranges from 0 °C to 70 °C, respectively. The significant advantage of our proposed sensor is its simple, compact, and easy-to-prepare structure, which opens up a new direction for device miniaturization.