Multi-parameter Simultaneously Sensing Based on an Optimized Concatenated FBG with LPG

Abstract

AbstractWe analyze an optical fiber sensor based on a concatenated fiber Bragg grating (FBG) with long period grating (LPG) with transfer matrix method and experiment. First, we optimize parameters of concatenated structure in the method of simulation and discuss the influence that the lengths, periods and dc induced index changes of FBG and LPG and length of optical fiber between LPG and FBG has to influence reflection spectrum. Second, based on the optimized parameters for concatenated structure, fabricate such structure and use it to monitor concentration and temperature simultaneously. Simulation result proves that increasing the lengths of FBG and LPG properly, and length of optical fiber between LPG and FBG fixed in 20 mm, more clearly reflection spectrum can be obtained. Experiment result shows a novel optical fiber sensor based on a concatenated strong fiber Bragg grating with a weak long period grating (CLBG) device can be used to monitor concentration and temperature simultaneously. The result of research has reference value in multi-parameter simultaneously sensing.