Multiparameter Sensor Based on Cascaded Micro-Tapered Long Period Fiber Gratings

To realize multiparameter simultaneous sensing measurement and eliminate cross-sensitivity, we cascade three micro-tapered long period fiber grating (TLPG) sensors and analyze the transmission characteristics and sensing capabilities of cascaded micro-tapered long period fiber gratings (CTLPG) in detail. Based on the modulation of the resonant wavelength of the sensor by the change of the surrounding environment, the synchronous real-time detection of refractive index (RI), temperature, and liquid level is realized. The CTLPG sensor, not only inherits the advantages of TLPG sensors, and reduces the influence of cross-sensitivity when measuring multiparameters, but also improves the sensitivity and accuracy of the sensor. Experimental results show that the maximum RI sensitivity is 693 nm/RIU, the maximum temperature sensitivity is -93 pm/°C, and the maximum liquid level sensitivity is 12 nm/mm. The sensor has a simple structure, low manufacturing cost, high sensitivity, and potential applications in monitoring ocean temperature, salinity, and depth.