Temperature and acoustic impedance simultaneous sensor based on forward stimulated Brillouin scattering in highly nonlinear fiber

Abstract A temperature and acoustic impedance simultaneous sensor based on forward stimulated Brillouin scattering (FSBS) in highly nonlinear fiber (HNLF) with high sensitivity and high accuracy is proposed and demonstrated in this paper. High-order acoustic modes (HOAMs) are used to achieve individual or simultaneous measurement of the two parameters. Transverse acoustic waves (TAWs) involved in the FSBS process can efficiently sense the mechanical or environmental changes outside the fiber cladding, which will be reflected in a linear shift of the acoustic resonance frequency. By analyzing the frequencies of specific scattering peaks, the temperature and acoustic impedance outside the fiber cladding can be obtained simultaneously. The highest measured temperature and acoustic impedance sensitivities are 184.93 kHz/°C and 444.56 kHz/MRayl, and the measurement accuracies are 0.09 °C and 0.009 MRayl, respectively, which are both at desirable levels. We believe this work can provide potential application solutions for sensing fields involving temperature or acoustic impedance measurements.