The reflective intensity modulated acoustical sensor with inclined fibers

An acoustic sensor based on the reflective intensity modulated fiber optic sensing principle was described in this paper. The angle between the transmitting fiber and the receiving fiber was fixed at 60° through the optic fiber module in the sensor, the acoustic signals were sensed and the optic signal intensity was modulated by the reflective vibration membrane manufactured by the micro-machined technique. The theoretical model of the sensor is established. The simulation and experimental results showed that the optimum distance of the system was 8 μm and the sensitivity was 2.49 μW/μm. The test results indicated that the sensor prototype has the sensitivity of 30 mV/Pa to the acoustic signal. The test results of the frequency response and linear response were also given in this paper.