Highly discriminative simultaneous measurement of level, refractive index and temperature of liquid by dual-wavelength fiber ring-cavity laser sensor

In this paper, a novel dual-wavelength fiber laser sensor is proposed and completed by the parallel configuration of modified fiber Bragg grating and modal interferometer. The stable lasing emissions are realized and the comprehensive tests are performed in terms of level, refractive index and temperature of liquid. By the demodulation of joint wavelength and intensity matrix, high-discriminative simultaneous measurement is ach-ieved, and the obtained sensitivities are 19.88 pm/degrees C, 159.32 dB/RIU and 568 pm/mm, respectively, with the errors below 2.52 %. Additionally, the dynamic field tests are performed, and the limits of detection of 0.15 mm, 0.42 degrees C and 9 x 10-4 RIU are experimentally verified.