Enhanced-sensitive dual microfiber knot resonators based sensor with vernier effect for simultaneous measurement of refractive index and temperature

In this paper, an sensitive-enhanced dual microfiber knot resonators (DMKRs) sensor based on Vernier effect for simultaneous sensing of Refractive index (RI) and temperature has been proposed and demonstrated. Because the spectral characteristics of the two resonators satisfy the production conditions of Vernier effect, the enhanced RI sensitivity of − 12523 nm/ RIU can be obtained by demodulating the Vernier envelope, which is 40 times of that for single microfiber knot resonator (MKR) sensor. However, the crosstalk of saline water temperature is also amplified to 0.91998 nm/℃. Based on the different response sensitivities of Vernier dip, high frequency dip and the sensitivity matrices, we realized the simultaneous detection of RI and temperature. This sensor demonstrated here show the advantages of easy fabrication, low cost and provides an excellent detection option for high sensitivity and small size in RI detection.