Fiber Bragg grating applied multi-functional sensor based on pulsed photoacoustic technique

Abstract

A multi-functional sensor based on a pulsed photoacoustic (PA) technique is proposed. This sensor can simultaneously measure the chemical concentration, temperature, and flow speed of liquid using only one fiber Bragg grating. The concentration and flow speed of a sample liquid can be estimated by analyzing both the “shape” and the “amplitude” of a PA waveform observed with an oscilloscope. The DC voltage, which is biased on the PA signal, also depends only on the static temperature of the liquid. Our metal-free sensor head, which is basically maintenance free, is substantially noise proof without electro-magnetical shielding. We demonstrated that our proposed sensor functions as a multi-functional sensor within a concentration range from 1000 to 10,000 ppm with a Rhodamine 6G solution.